Pyridazinyl derivatives as smo inhibitors

ABSTRACT

The present invention relates to compounds of formula I: 
     
       
         
         
             
             
         
       
         
         
           
             in which R11 and R12 are defined in the Summary of the Invention; capable of inhibiting the Hedgehog and Smo signaling pathway. The invention further provides a process for the preparation of compounds of the invention, pharmaceutical preparations comprising such compounds and methods of using such compounds and compositions in the diagnosis and treatment of pathologies relating to the Hedgehog and Smo signaling pathway, for example, tumor formation, cancer, neoplasia and non-malignant hyperproliferative disorders.

This application claims priority to U.S. Provisional Application Ser.No. 61/081,900 filed 18 Jul. 2008, the contents of which areincorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

Hedgehog (Hh) signaling was first identified in Drosophila as animportant regulatory mechanism for embryonic pattern formation, or theprocess by which embryonic cells form ordered spatial arrangements ofdifferentiated tissues (Nusslein-Volhard et al. (1980) Nature 287,795-801). In mammalian cells, three Hedgehog genes, Sonic Hedgehog(Shh), Indian Hedgehog (Ihh) and Desert Hedgehog (Dhh), have beenidentified. Hedgehog genes encode secreted proteins, which undergopost-translational modifications, including autocatalytic cleavage andlipid modification (palmitoylation) at the N-terminus and cholesterolmodification of the C-terminus.

The lipid-modified N-terminal Hedgehog protein triggers the signalingactivity of the protein pathway, and cell to cell communication isengendered by the dispatch of soluble Hedgehog protein from a signalingcell and receipt by a responding cell. In responding cells, the 12-passtransmembrane receptor Patched (Ptch) acts as negative regulator of Hhsignaling and the 7-pass transmembrane protein Smoothened (Smo) acts asa positive regulator of Hh signaling. At resting state, free Ptch (i.e.,unbound by Hh) substoichiometrically suppresses pathway activity inducedby Smo (Taipale et al. (2002) Nature 418: 892); upon binding ligand Hhprotein, however, repression of Smo is relieved, and the resultingsignaling cascade leads to the activation and nuclear translocation ofGli transcription factors (Gli1, Gli2 and Gli3).

Downstream target genes of Hh signaling transcription include Wnts,TGFβ, and Ptc and Gli1, which are elements of the positive and negativeregulatory feedback loop. Several cell-cycle and proliferationregulatory genes, such as c-myc, cyclin D and E are also among thetarget genes of Hh signaling.

Hh signaling is known to regulate a diverse range of biologicalprocesses, such as cellular proliferation, differentiation, and organformation in a tissue specific and dose dependent manner. In thedevelopment of neural tubes, Shh is expressed in the floorplate anddirects the differentiation of specific subtypes of neurons, includingmotor and dopaminergic neurons. Hh is also known to regulate theproliferation of neuronal progenitor cells, such as cerebella granulecells and neural stem cells. In the developing intestinal tract, alow-level of Hh signaling is required for pancreatic development, whilea high-level of Hh signaling blocks pancreatic organogenesis. Hh is alsoknown to play important roles in stem cell proliferation andorganogenesis in skin, prostate, testis and bone marrow.

Normally, Hh signaling is strictly controlled during cellularproliferation, differentiation and embryonic pattern formation. However,aberrant activity of the Hedgehog signaling pathway, due to mutationsthat constitutively activate the pathway, for instance, may havepathological consequences. By way of example, loss-of-function mutationsof Patched are found in Gorlin's syndrome (a hereditary syndrome withhigh risk of skin and brain cancers, also known as Basal Cell NevusSyndrome (BCNS)); and gain-of-function mutations of Smo and Gli arelinked to basal cell carcinoma and glioblastoma. Basal cell carcinoma(BCC) is the most common form of skin cancer, affecting more than 90,000Americans each year. Constitutive activation of Hh has been found topromote tumorigenesis in BCC, medulloblastoma (the most common childhoodbrain tumor), rhabdomyosarcoma, pancreatic cancer, small cell lungcancer, prostate cancer and breast cancer. Besides the roles intumorigenesis, Hh signaling is also implicated in the metastasis ofprostate cancer. Hh signaling may be involved in many additional typesof tumors and such links are expected to continue to be discovered; thisis an area of active research in many cancer centers around the world.

Proliferation of these cancer cells requires Hh pathway activation, andblocking Hh signaling pathways often inhibits cancer cell proliferation.Indeed, Hh antagonist cyclopamine and Gli1 siRNA can effectively blockthe proliferation of these cancer cells, and can reduce tumor size inXenograft models, suggesting that novel Hh antagonists could provide newchemotherapeutic agents for the treatment of these cancers. Hhantagonist cyclopamine has been shown to suppress the metastasis ofprostate cancer in animal models.

In addition to being involved in cancer, Hh signaling plays importantroles in normal tissue homeostasis and regeneration. Hh pathway isactivated after the injury of retina, bile duct, lung, bone and prostatein mouse models. Hh pathway is also constantly active in hair follicles,bone marrow, and certain regions of the central nervous system (CNS),and benign prostate hyperplasia and blood vessel formation in wetmacular degeneration require Hedgehog pathway activity. Cellularregeneration processes can be blocked by anti-Shh antibody andcyclopamine. Therefore, small molecule antagonists of Hh signalingpathway might be useful in the treatment of neuronal proliferativediseases, benign prostate hyperplasia, wet macular degeneration,psoriasis, bone marrow proliferative diseases and leukemias,osteopetrosis and hair removal.

Evidence that constitutive activation of Smo results in cancers (e.g.,BCC), and that Smo may be oncogenic upon its release from inhibition byPtch, suggests utility of Smo antagonists as therapeutic agents in thetreatment of such disorders. (Stone et al. (1996) Nature 384: 129).Accordingly, molecules that modulate the activity of the Hedgehogsignaling pathway, e.g., which modulate Smo activity, aretherapeutically useful.

SUMMARY OF THE INVENTION

The present invention relates generally to novel compounds relating tothe diagnosis and treatment of pathologies relating to the Hedgehogpathway, including but not limited to tumor formation, cancer,neoplasia, and non-malignant hyperproliferative disorders. The presentinvention includes novel compounds, novel compositions, methods of theiruse and methods of their manufacture, where such compounds are generallypharmacologically useful as agents in therapies whose mechanism ofaction involve methods of inhibiting tumorigenesis, tumor growth andtumor survival using agents that inhibit the Hedgehog and Smo signalingpathway. The compounds and methods of the present invention (e.g., acompound of Formula I) relate to inhibiting activation of the Hedgehogsignaling pathway, e.g., by inhibiting aberrant growth states resultingfrom phenotypes such as Ptc loss-of-function, Hedgehog gain-of-function,Smoothened gain-of-function or Gli gain-of-function, and comprisecontacting the cell with a compound of the invention (e.g., a compoundof Formula I) in a sufficient amount to agonize a normal Ptc activity,antagonize a normal Hedgehog activity, or antagonize Smoothened activity(e.g., to reverse or control the aberrant growth state).

The present invention relates to compounds of the formula (I):

or a pharmaceutically acceptable salt thereof, wherein

R1 is a C₆₋₁₄ an group, or a 5-14 membered heteroaryl group which may beunsubstituted or substituted by one or more of C₁₋₈ alkyl, a C₆₋₁₄ angroup, C₁₋₈ haloalkyl, C₁₋₈ alkoxy, halo, NH₂, CN, OCF₃, OH, C(O)NR6R8,C(O)R6, NR6R8, NHC(O)R6, SO₂R6, or SO₂NR6R8;

R2 and R3 are independently C₁₋₈ alkyl, C₁₋₈ alkylOH, or R2 and R3 forma fused C₃₋₁₄ cycloalkyl group;

L is a bond, C₁₋₈ alkylene, —C(O)O—, —C(O)NR9-, —C₁₋₈ alkylOH—, —C₁₋₈haloalkyl-, —C(O)—, —NH— or —O—;

X and W are independently N or CR5, and at least one of X or W is N;

R7 is a C₆₋₁₄ aryl group, a 5-14 membered heteroaryl group, or a 3-14membered cycloheteroalkyl group;

R4 is C₁₋₈ alkyl, C₂₋₈ alkenyl, C₃₋₁₄ Cycloalkyl, a C₆₋₁₄ aryl group, a5-14 membered heteroaryl group, a 3-14 membered cycloheteroalkyl group,C₁₋₈ alkoxy, halo, NR6R8, C(O)OR6, C(O)NR6R8, C₁₋₈haloalkyl, formyl,carbalkoxy, C₁₋₈alkylOH, C(O)R6, SO₂R6, C(O)NHC₁₋₈alkylR6, NR6R8,SO₂NR6R8, OCF₃, NHC(O)R6, CH₂OC(O)NR6R8, CH₂NR6R8, NHC(O)OR6,NHC(O)NR6R8, CH₂NHSO₂R6, CH₂NHC(O)OR6, OC(O)R6, or NHC(O)R6, which maybe substituted or unsubstituted;

Z is C₁₋₈ alkyl, CN, OH, or halogen;

m and p are independently 0-3;

Y is a bond, C₁₋₈ alkylene, —C(O)—, —C(O)O—, —CH(OH)—, or —C(O)NR10;

R5 is H, halogen, CN, lower alkyl, OH, OCH₃ or OCF₃;

R9 and R10 are independently C₁₋₈ alkyl or H;

R6 and R8 are independently H, C₁₋₈ alkyl, C₂₋₈ alkenyl, C₃₋₁₄cycloalkyl, a C₆₋₁₄ an group, a 5-14 membered heteroaryl group, a 3-14membered cycloheteroalkyl group, C₁₋₈haloalkyl, C₁₋₈ alkylOH,C₁₋₈alkoxy, or two R6, or an R6 and a R8 on one atom can form aheteroatom containing ring; and

Wherein R4, R6, and R8 can be unsubstituted or substituted by one ormore of C₁₋₈ alkyl, C₃₋₁₄ cycloalkyl, a C₆₋₁₄ an group, a 5-14 memberedheteroaryl group, a 3-14 membered cycloheteroalkyl group, C₁₋₈ alkylOH,OH, oxo, C₁₋₈ haloalkyl, carboxC₁₋₈ alkyl, or SO₂C₁₋₈alkyl, halo, —OCH₃,—OCF₃, —OH, —NH₂.

In an embodiment, the present invention includes compounds of formula(I) wherein R7 is

In another embodiment, the present invention includes compounds offormula (I) according to claim 1 wherein R1 is

In another embodiment, the present invention includes compounds offormula (I) wherein R7 is

In yet another embodiment, the present invention includes compounds offormula (I) wherein R4 is C(O)OC₁₋₈ alkyl, CF₃, C(O)OR6, C(O)NR6R8, C₁₋₈haloalkyl, C₁₋₈ alkylOH, C(O)R6, SO₂R6, C(O)NHC₁₋₈ alkylR6,C(CH₃)(CH₃)(OH), C(O)CH₃, C(CH₂)CH₃, or C(CH₃)(CH₂OH)OH; and R6 and R8are independently H, C₁₋₈ alkyl, C_(is) alkenyl, C₃₋₁₄ cycloalkyl, aC₆₋₁₄ aryl group, a 5-14 membered heteroaryl group, or a 3-14 memberedcycloheteroalkyl group.

In another embodiment, the present invention includes compounds offormula (I) wherein R7 is

and R4 is C₁₋₈ alkyl, such as methyl, ethyl, proply, or butyl; C₂₋₈alkenyl, such as ethenyl or propenyl; C₃₋₁₄ cycloalkyl, such ascyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl; a C₆₋₁₄ aryl group,such as phenyl; a 5-14 membered heteroaryl group, such as pyridinyl orimidazolyl, a 3-14 membered cycloheteroalkyl group, such as piperidinyl,morpholinyl, pyrrolidinyl, or piperazinyl; C₁₋₈ alkoxy, such as methoxy,ethoxy, or propoxy; halo, such as Cl, F, Br, or I; NR6R8, such asNHC₁₋₈alkyl; C(O)OR6, such as C(O)OC₁₋₈alkyl, or C(O)OH; C(O)NR6R8, suchas C(O)NHC₆₋₁₄aryl, C(O)NC₆₋₁₄arylC₁₋₈alkyl, or C(O)-5-14 memberedheteroaryl group, or C(O)-3-14 membered cycloheteroalkyl group,C₁₋₈haloalkyl, such as CF₃; formyl, carbalkoxy, C₁₋₈alkylOH, such asCH₂OH, ethyl substituted with OH at any position, propyl substitutedwith OH at any position, or butyl substituted with OH at any position;C(O)R6, such as C(O)C₁₋₈alkyl; SO₂R6, such as SO₂C₁₋₈alkyl or SO₂CF₃;C(O)NHC₁₋₈alkylR6, such as C(O)NHC₁₋₈alkylOH, or C(O)NHC₁₋₈alkylCF₃;SO₂NR6R8, such as SO₂NHC1-8alkyl; OCF₃, NHC(O)R6, such asNHC(O)C₁₋₈alkyl; CH₂OC(O)NR6R8, CH₂NR6R8, NHC(O)OR6, NHC(O)NR6R8,CH₂NHSO₂R6, CH₂NHC(O)OR6, OC(O)R6, or NHC(O)R6, and wherein R4 may beunsubstituted or substituted; and p is 0, 1, or 2.

In another embodiment, R6 and R8 are independently H, C₁₋₈ alkyl, suchas methyl, ethyl, propyl, or butyl; C₂₋₈ alkenyl, such as alkenyl,propenyl; C₃₋₁₄ cycloalkyl, such as cyclopropyl, cyclobutyl,cyclopentyl, or cyclohexyl; a C₆₋₁₄ aryl group, such as phenyl; a 5-14membered heteroaryl group, such as pyridinyl or pyrimidinyl; a 3-14membered cycloheteroalkyl group, such as morpholinyl, piperidinyl,pyrrolidinyl, or piperazinyl; C₁₋₈haloalkyl, such as CF₃; C₁₋₈ alkylOH,C₁₋₈alkoxy, such as methoxy or ethoxy; or two R6, or R6 and R8 on oneatom can form a heteroatom containing ring, such as a 5-14 memberedheteroaryl group or a 3-14 membered cycloheteroalkyl group.

In another embodiment of the present invention, R4 may be unsubstitutedor substituted with one or more of C₁₋₈ alkyl, such as methyl, ethyl,propyl, butyl, or pentyl; C₃₋₁₄ cycloalkyl, such as cyclopropyl,cyclobutyl, cyclopentyl, or cyclohexyl; a C₆₋₁₄ aryl group, such asphenyl; a 5-14 membered heteroaryl group, such as pyridinyl orpyrimidinyl; a 3-14 membered cycloheteroalkyl group, such asmorpholinyl, piperidinyl, pyrrolidinyl, or piperazinyl; C₁₋₈ alkylOH,such as CH₃OH; OH, oxo, C₁₋₈ haloalkyl, such as CF₃; carboxyC₁₋₈alkyl,or SO₂C₁₋₈alkyl, halo, such as Cl, F, Br, or I; —OCH₃, —OCF₃, or —NH₂.

In another embodiment, and R4 is methyl, phenyl, pyridinyl, methoxy, Cl,F, C(O)OC₁₋₈alkyl, C(O)OH, C(O)NHC₆₋₁₄aryl, C(O)NC₆₋₁₄arylC₁₋₈alkyl,C(O)-5-14 membered heteroaryl group, C(O)-3-14 membered cycloheteroalkylgroup, CF₃; CH₂OH, CH₂CH₂OH, C(CH₃)(CH₃)OH, C(O)CH₃, C(O)CH₂CH₃,SO₂C₁₋₈alkyl, SO₂CF₃, C(O)NHC₁₋₈alkylOH, C(O)NHC₁₋₈alkylCF₃,SO₂NHC₁₋₈alkyl, OCF₃, NHC(O)CH₃, or CH₂OC(O)NHCH₃; each of which may beunsubstituted or substituted; and p is 0, 1, or 2.

In another embodiment, R4 is C(O)CH₃, C(O)NH-phenyl, C(O)OH, CF₃,C(CH₃)(CH₃)OH, C(O)OCH₃, CF₃, C(O)OCH₂CH₃, or C(O)NCH₂CH₃, optionallysubstituted with piperazinyl, morpholinyl, or pyridinyl.

In a preferred embodiment, R7 is

andR4 is C(O)CH₃, C(O)NH-phenyl, C(O)OH, CF₃, C(CH₃)(CH₃)OH, C(O)OCH₃, CF₃,or C(O)OCH₂CH₃.

In another embodiment, the present invention includes compounds offormula (I) wherein R1 is

each of which may be unsubstituted or substituted by one or more of C₁₋₈alkyl, such as methyl, ethyl, propyl (e.g., isopropyl), butyl, pentyl,or hexyl; a C₆₋₁₄ aryl group, such as phenyl; C₁₋₈ haloalkyl, such asCF3; C₁₋₈ alkoxy, such as methoxy or ethoxy; halo, such as Cl, F, Br, orI; NH₂, CN, OCF₃, OH, C(O)NR6R8, C(O)R6, NR6R8, NHC(O)R6, SO₂R6, orSO₂NR6R8.

In a further embodiment, R1 is

which may be unsubstituted or substituted with each of which may beunsubstituted or substituted by one or more of methyl, ethyl, CF3,methoxy, Cl, F, NH₂, CN, OCF₃, or OH. In another embodiment, R1 may beunsubstituted or substituted with CH₃, Cl, F, methoxy, or CH.

In another embodiment, the present invention includes compounds offormula (I) wherein R7 is

andR1 is

which may be unsubstituted or substituted with one or more of methyl,ethyl, isopropyl, Cl, F, CN, methoxy, or CF₃.

In yet another embodiment, the present invention includes compounds offormula (I) wherein R4 is C(O)OC₁₋₈ alkyl, CF₃, C(O)OR6, C(O)NR6R8, C₁₋₈haloalkyl, C₁₋₈ alkylOH, C(O)R6, SO₂R6, C(O)NHC₁₋₈alkylR6,C(CH₃)(CH₃)(OH), C(O)CH₃, CH₂—CH₂—CH₃, or C(CH₃)(CH₇OH)OH.

In an embodiment R6 and R8 are independently H, methyl, ethyl,cyclopentyl, cyclohexyl, phenyl, pyridinyl, morpholinyl, piperidinyl,pyrrolidinyl, or piperazinyl, CF₃, methoxy, two R6, or R6 and R8 on oneatom can form a heteroatom containing ring, such as a 5-14 memberedheteroaryl group, such as pyridinyl or pyrimidinyl; or a 3-14 memberedcycloheteroalkyl group, such as piperidinyl or piperazinyl.

In another embodiment, the present invention includes compounds offormula (I) wherein R4 is

which may be unsubstituted or substituted.

In another embodiment, the present invention includes compounds offormula (I) wherein R2 and R3 are C₁₋₈ alkyl, such as methyl, ethyl, ortogether with the carbon atoms to which they are attached form aC₄₋₇cycloalkyl group. In another embodiment, R2 and R3 are each methyl,or form a cyclopentyl or cyclohexyl group.

In a still further embodiment, the present invention includes compoundsof formula (I) wherein R2 and R3 are CH₃.

In another embodiment, the present invention includes compounds offormula (I) wherein L is —O—, —NH—, —C(O)—, —CH(OH)—, —CH₂—, —CF₂—,—CHF—, —C(OH)—, or a bond. In another embodiment, the present inventionincludes compounds of formula (I) wherein L is —CH₂—. In anotherembodiment, the present invention includes compounds of formula (I)wherein both X and W are N, and Z is CH₃, and m is 1.

In another embodiment, p is 0, 1, or 2. In another embodiment, p is 0or 1. In yet another embodiment, p is 1.

In another embodiment, Y is a bond, C₁₋₈ alkylene, such as methylene,ethylene, propylene —C(O)—, —C(O)O—, —CH(OH)—, or —C(O)NR10, where R10is C₁₋₈alkyl, such as methyl, ethyl, propyl, or butyl, or H. In anotherembodiment, Y is a bond, methylene, —C(O)O—, or C(O)NH. In anotherembodiment, Y is a bond.

In another embodiment, the present invention includes a compound offormula (Ia):

or a pharmaceutically acceptable salt thereof, wherein

R11 is C₁₋₃ alkyl, C₂₋₈ alkenyl, C₃₋₁₄ cycloalkyl, a C₆₋₁₄ an group, a5-14 membered heteroaryl group, a 3-14 membered cycloheteroalkyl group,C₁₋₈ alkoxy, halo, NR13R14, C(O)OR13, C(O)NR13R14, C₁₋₈haloalkyl,formyl, carbalkoxy, C₁₋₈alkylOH, C(O)R13, SO₂R13, C(O)NHC₁₋₈alkylR13,NR13R14, SO₂NR13R14, OCF₃, NHC(O)R13, CH₂OC(O)NR13R14, CH₂NR13R14,NHC(O)OR13, NHC(O)NR13R14, CH₂NHSO₂R13, CH₂NHC(O)OR13, OC(O)R13, orNHC(O)R13, which may be substituted or unsubstituted;

R12 is H, C₁₋₈ alkyl, a C₆₋₁₄ an group, C₁₋₈ haloalkyl, C₁₋₈ alkoxy,halo, NH₂, CN, OCF₃, OH, C(O)NR13R14, C(O)R13, NR13R14, NHC(O)R13,SO₂R13, SO₂NR13R14;

R13 and R14 are independently H, C₁₋₈ alkyl, C₂₋₈ alkenyl, C₃₋₁₄cycloalkyl, a C₆₋₁₄ aryl group, a 5-14 membered heteroaryl group, a 3-14membered cycloheteroalkyl group, C₁₋₈haloalkyl, C₁₋₈alkylOH, C₁₋₈alkoxy,or R13 and R14 on one atom can form a heteroatom containing ring; and

Wherein R11, R13, and R14 can be unsubstituted or substituted by one ormore of C₁₋₈ alkyl, C₃₋₁₄ cycloalkyl, a C₆₋₁₄ an group, a 5-14 memberedheteroaryl group, a 3-14 membered cycloheteroalkyl group, C₁₋₈ alkylOH,OH, oxo, C₁₋₈ haloalkyl, carboxC₁₋₈ alkyl, or SO₂C₁₋₈alkyl, halo, —OCH₃,—OCF₃, —OH, —NH₂.

In another embodiment, the present invention includes a compoundselected from:

-   2-[(R)-4-(4,5-Dimethyl-6-phenoxy-pyridazin-3-yl)-2-methyl-3,4,5,6-tetra-hydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol;-   2-{(R)-4-[6-(Hyrdoxyl-phenyl-methyl0-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2]bipyrazinyl-5′-yl]-propan-2-ol;-   2-[(R)-4-(4,5-Dimethyl-6-pyridin-4-ylmethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol;-   2-[(R)-4-(4,5-Dimethyl-6-pyridin-2-ylmethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol;-   2-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol;-   2-[4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′yl]-propan-2-ol;-   2-[(S)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol;-   2-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-ethyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol;-   2-[4-(4-Benzyl-6,7-dihydro-5H-cyclopenta[d]pyridazin-1-yl)-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol;-   2-[(R)-4-(4-Benzyl-6,7-dihydro-5H-cyclopenta[d]pyridazin-1-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol;-   1-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-ethanone;    and-   2-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propane-1,2-diol.

One aspect of the present invention makes available methods employingcompounds for inhibiting Smo-dependent pathway activation. Anotheraspect of the present invention makes available methods employingcompounds for inhibiting Hedgehog (ligand)-independent pathwayactivation. In certain embodiments, the present methods can be used tocounteract the phenotypic effects of unwanted activation of a Hedgehogpathway, such as resulting from Hedgehog gain-of-function, Ptcloss-of-function or smoothened gain-of-function mutations. For instance,the subject method can involve contacting a cell (in vitro or in vivo)with a Smo antagonist, such as a compound of the invention (e.g., acompound of Formula I) or other small molecule in an amount sufficientto antagonize a smoothened-dependent and/or Hedgehog independentactivation pathway.

The compounds and methods of the present invention may be used toregulate proliferation and/or differentiation of cells in vitro and/orin vivo, e.g., in the formation of tissue from stem cells, or to preventthe growth of hyperproliferative cells. In another particularembodiment, contacting the cell with—or introducing into the cell—acompound of the invention (e.g., a compound of Formula I) results ininhibition of cellular proliferation, inhibition of tumor cell growthand/or survival, and/or inhibition of tumorigenesis. Thus, anotherparticular embodiment provides methods for inhibiting and/orantagonizing the Hh pathway by employing compounds of the invention(e.g., a compound of Formula I) in a tumor cell.

The methods of the present invention may employ compounds of theinvention (e.g., a compound of Formula I) as formulated aspharmaceutical preparations comprising a pharmaceutically acceptableexcipient or carrier, and said preparations may be administered to apatient to treat conditions involving unwanted cell proliferation suchas cancers and/or tumors (such as medullablastoma, basal cell carcinoma,etc.), and non-malignant hyperproliferative disorders.

One embodiment of the present invention provides a compound and methodfor inhibiting the synthesis, expression, production, stabilization,phosphorylation, relocation within the cell, and/or activity of a Smoprotein in a cell in vitro or in vivo comprising, contacting said cellwith, or introducing into said cell, a compound of the invention (e.g.,a compound of Formula I).

Another aspect of the invention provides a compound and method ofdiagnosing, preventing and/or treating cellular debilitations,derangements, and/or dysfunctions; hyperplastic, hyperproliferativeand/or cancerous disease states; and/or metastasis of tumor cells, in amammal characterized by the presence and/or expression of a Smo gene orgene product (e.g., a Smo protein), comprising compounds of formula (I)and their administration to a mammal in a therapeutically effectiveamount.

DETAILED DESCRIPTION OF THE INVENTION

In another embodiment, the present invention includes a pharmaceuticalcomposition comprising a therapeutically effective amount of a compoundaccording to formula I or Ia. In another embodiment, the presentinvention includes a method of treating a mammal suffering from apathology relating to the Hedgehog pathway which comprises administeringto said mammal in need of treatment a therapeutically effective amountof a compound according to formula I or Ia.

In the present description, the term “treatment” includes bothprophylactic or preventive treatment as well as curative or diseasesuppressive treatment, including treatment of patients at risk for adisorder of the invention (e.g., a Hedgehog-related disorder (e.g.,cancer)) as well as ill patients. This term further includes thetreatment for the delay of progression of the disease.

By “suppress and or reverse,” e.g., a Hedgehog-related disorder (e.g.,cancer), Applicants mean to abrogate said Hedgehog-related disorder(e.g., diabetes), or to render said condition less severe than before orwithout the treatment.

“Cure” as used herein means to lead to the remission of theHedgehog-related disorder (e.g., cancer) in a patient, or of ongoingepisodes thereof, through treatment.

The terms “prophylaxis” or “prevention” means impeding the onset orrecurrence of metabolic disorders, e.g., diabetes.

“Treatment” or “treating” refers to therapy, prevention and prophylaxisand particularly refers to the administration of medicine or theperformance of medical procedures with respect to a patient, for eitherprophylaxis (prevention) or to cure or reduce the extent of orlikelihood of occurrence of the infirmity or malady or condition orevent in the instance where the patient is afflicted.

“Diagnosis” refers to diagnosis, prognosis, monitoring, characterizing,selecting patients, including participants in clinical trials, andidentifying patients at risk for or having a particular disorder orclinical event or those most likely to respond to a particulartherapeutic treatment, or for assessing or monitoring a patient'sresponse to a particular therapeutic treatment.

“Subject” or “patient” refers to a mammal, preferably a human, in needof treatment for a condition, disorder or disease.

“A compound(s) of the invention” as used herein includes but is notlimited to compounds of Formula I (e.g., a compound of Formulae (I),including all variants thereof). A compound of the invention includesthe specifically listed compounds listed herein, including those listedin the Examples of the present application.

“Delay of progression” as used herein means that the administration of acompound of the invention (e.g., a compound of Formula I) to patients ina pre-stage or in an early phase of a Hedgehog-related disorder (e.g.,cancer) prevents the disease from evolving further, or slows down theevolution of the disease in comparison to the evolution of the diseasewithout administration of the active compound.

“Hedgehog gain-of-function” refers to an aberrant modification ormutation of a Ptc gene, Hedgehog gene, or smoothened gene, or a change(e.g., decrease) in the level of expression of such a gene, whichresults in a phenotype which resembles contacting a cell with a Hedgehogprotein, e.g., aberrant activation of a Hedgehog pathway. Thegain-of-function may include a loss of the ability of the Ptc geneproduct to regulate the level of expression of Gli genes, e.g., Gli1,Gli2, and Gli3, or loss of the ability to regulate the processing,stability, localization or activity of the Gli proteins, e.g., Gli1,Gli2, and Gli3. The term “Hedgehog gain-of-function” is also used hereinto refer to any similar cellular phenotype (e.g., exhibiting excessproliferation) which occurs due to an alteration anywhere in theHedgehog signal transduction pathway, including, but not limited to, amodification or mutation of Hedgehog itself. For example, a tumor cellwith an abnormally high proliferation rate due to activation of theHedgehog signaling pathway would have a “Hedgehog gain-of-function”phenotype, even if Hedgehog is not mutated in that cell.

“Patched loss-of-function” refers to an aberrant modification ormutation of a Ptc gene, or a decreased level of expression of the gene,which results in a phenotype which resembles contacting a cell with aHedgehog protein, e.g., aberrant activation of a Hedgehog pathway. Theloss-of-function may include a loss of the ability of the Ptc geneproduct to regulate the level of expression, processing, stability,localization, regulation or activity of Gli genes and proteins, e.g.,Gli1, Gli2 and Gli3.

“Gli gain-of-function” refers to an aberrant modification or mutation ofa Gli gene, or an increased level of expression of the gene, whichresults in a phenotype which resembles contacting a cell with a Hedgehogprotein, e.g., aberrant activation of a Hedgehog pathway.

“Smoothened gain-of-function” refers to an aberrant modification ormutation of a Smo gene, or an increased level of expression of the gene,which results in a phenotype which resembles contacting a cell with aHedgehog protein, e.g., aberrant activation of a Hedgehog pathway.

As used herein a “small organic molecule” is an organic compound (ororganic compound complexed with an inorganic compound (e.g., metal))that has a molecular weight of less than 3 kilodaltons, and preferablyless than 1.5 kilodaltons.

As used herein a “reporter” gene is used interchangeably with the term“marker gene” and is a nucleic acid that is readily detectable and/orencodes a gene product that is readily detectable such as luciferase.

Transcriptional and translational control sequences are DNA regulatorysequences, such as promoters, enhancers, terminators, and the like, thatprovide for the expression of a coding sequence in a host cell. Ineukaryotic cells, polyadenylation signals are control sequences.

A “promoter sequence” is a DNA regulatory region capable of binding RNApolymerase in a cell and initiating transcription of a downstream (3′direction) coding sequence. For purposes of defining the presentinvention, the promoter sequence is bounded at its 3′ terminus by thetranscription initiation site and extends upstream (5′ direction) toinclude the minimum number of bases or elements necessary to initiatetranscription at levels detectable above background. Within the promotersequence will be found a transcription initiation site (convenientlydefined for example, by mapping with nuclease S1), as well as proteinbinding domains (consensus sequences) responsible for the binding of RNApolymerase.

A coding sequence is “under the control” of transcriptional andtranslational control sequences in a cell when RNA polymerasetranscribes the coding sequence into mRNA, which is then trans-RNAspliced and translated into the protein encoded by the coding sequence.

The phrase “pharmaceutically acceptable” refers to molecular entitiesand compositions that are physiologically tolerable and do not typicallyproduce an allergic or similar untoward reaction, such as gastric upset,dizziness and the like, when administered to a human. Preferably, asused herein, the term “pharmaceutically acceptable” means approved by aregulatory agency of the Federal or a state government or listed in theU.S. Pharmacopeia or other generally recognized pharmacopeia for use inanimals, and more particularly in humans.

The term “carrier” refers to a diluent, adjuvant, excipient, or vehiclewith which the compound is administered. Such pharmaceutical carrierscan be sterile liquids, such as water and oils, including those ofpetroleum, animal, vegetable or synthetic origin, such as peanut oil,soybean oil, mineral oil, sesame oil and the like. Water or aqueoussolution saline solutions and aqueous dextrose and glycerol solutionsare preferably employed as carriers, particularly for injectablesolutions. Suitable pharmaceutical carriers are described in“Remington's Pharmaceutical Sciences” by E. W. Martin.

The phrase “therapeutically effective amount” is used herein to mean anamount sufficient to reduce by at least about 15 percent, preferably byat least 50 percent, more preferably by at least 90 percent, and mostpreferably prevent, a clinically significant deficit in the activity,function and response of the host. Alternatively, a therapeuticallyeffective amount is sufficient to cause an improvement in a clinicallysignificant condition/symptom in the host.

“Agent” refers to all materials that may be used to preparepharmaceutical and diagnostic compositions, or that may be compounds,nucleic acids, polypeptides, fragments, isoforms, variants, or othermaterials that may be used independently for such purposes, all inaccordance with the present invention.

“Analog” as used herein, refers to a small organic compound, anucleotide, a protein, or a polypeptide that possesses similar oridentical activity or function(s) as the compound, nucleotide, proteinor polypeptide or compound having the desired activity and therapeuticeffect of the present invention. (e.g., inhibition of tumor growth), butneed not necessarily comprise a sequence or structure that is similar oridentical to the sequence or structure of the preferred embodiment

“Derivative” refers to either a compound, a protein or polypeptide thatcomprises an amino acid sequence of a parent protein or polypeptide thathas been altered by the introduction of amino acid residuesubstitutions, deletions or additions, or a nucleic acid or nucleotidethat has been modified by either introduction of nucleotidesubstitutions or deletions, additions or mutations. The derivativenucleic acid, nucleotide, protein or polypeptide possesses a similar oridentical function as the parent polypeptide.

“Inhibitors,” or “antagonists” refer to inhibitory molecules identifiedusing in vitro and in vivo assays for Hh pathway function, e.g., Smoantagonists. In particular, inhibitors and antagonists refer tocompounds or agents that decrease signaling that occurs via the Hhpathway. Inhibitors may be compounds that decrease, block, or prevent,signaling via this pathway.

“Hedgehog-related disorder(s)” as used herein includes disordersassociated with disruption or aberrance of the Hedgehog pathway, as wellas disorders associated with normal but undesired growth states relatingto activation of the Hedgehog pathway. “Hedgehog-related disorder(s)”include but are not limited to tumor formation, cancer, neoplasia,malignant hyperproliferative disorders, and non-malignanthyperproliferative disorders. “Hedgehog-related disorder(s)” alsoinclude benign prostate hyperplasia, psoriasis, wet maculardegeneration, osteopetrosis and unwanted hair growth.

As used herein, the term “cancer” includes solid mammalian tumors aswell as hematological malignancies. “Solid mammalian tumors” includecancers of the head and neck, lung, mesothelioma, mediastinum,esophagus, stomach, pancreas, hepatobiliary system, small intestine,colon, colorectal, rectum, anus, kidney, urethra, bladder, prostate,urethra, penis, testis, gynecological organs, ovaries, breast, endocrinesystem, skin, central nervous system including brain; sarcomas of thesoft tissue and bone; and melanoma of cutaneous and intraocular origin.The term “hematological malignancies” includes childhood leukemia andlymphomas, Hodgkin's disease, lymphomas of lymphocytic and cutaneousorigin, acute and chronic leukemia, plasma cell neoplasm and cancersassociated with AIDS. In addition, a cancer at any stage of progressioncan be treated, such as primary, metastatic, and recurrent cancers.Information regarding numerous types of cancer can be found, e.g., fromthe American Cancer Society, or from, e.g., Wilson et al. (1991)Harrison's Principles of Internal Medicine, 12th Edition, McGraw-Hill,Inc. Both human and veterinary uses are contemplated.

Cancers which are particularly amenable to treatment by the compoundsand methods of the invention include but are not limited to gliomas,medulloblastomas, primitive neuroectodermal tumors (PNETS), basal cellcarcinoma (BCC), small cell lung cancers, large cell lung cancers,tumors of the gastrointestinal tract, rhabdomyosarcomas, soft tissuesarcomas, pancreatic tumors, bladder tumors and prostate tumors.

As used herein, the term “malignant hyperproliferative disorder(s)”includes but is not limited to cancers, neuronal proliferativedisorders, bone marrow proliferative diseases and leukemias.

As used herein, the term “non-malignant hyperproliferative disorder(s)”includes but is not limited to non-malignant and non-neoplasticproliferative disorders, such as smooth muscle hyperplasia in bloodvessels, cutaneous scarring, and pulmonary fibrosis.

As used herein, “halo” or “halogen” refers to fluoro, chloro, bromo, andiodo.

As used herein, “alkyl” refers to a straight-chain or branched saturatedhydrocarbon group. In some embodiments, an alkyl group can have from 1to 10 carbon atoms (e.g., from 1 to 8 carbon atoms). Examples of alkylgroups include methyl (Me), ethyl (Et), propyl (e.g., n-propyl andisopropyl), butyl (e.g., n-butyl, isobutyl, s-butyl, t-butyl), pentylgroups (e.g., n-pentyl, isopentyl, neopentyl), and the like. A loweralkyl group typically has up to 4 carbon atoms. Examples of lower alkylgroups include methyl, ethyl, propyl (e.g., n-propyl and isopropyl), andbutyl groups (e.g., n-butyl, isobutyl, s-butyl, t-butyl).

As used herein, “alkenyl” refers to a straight-chain or branched alkylgroup having one or more carbon-carbon double bonds. In someembodiments, an alkenyl group can have from 2 to 10 carbon atoms (e.g.,from 2 to 8 carbon atoms). Examples of alkenyl groups include ethenyl,propenyl, butenyl, pentenyl, hexenyl, butadienyl, pentadienyl,hexadienyl groups, and the like. The one or more carbon-carbon doublebonds can be internal (such as in 2-butene) or terminal (such as in1-butene).

As used herein, “alkynyl” refers to a straight-chain or branched alkylgroup having one or more carbon-carbon triple bonds. In someembodiments, an alkynyl group can have from 2 to 10 carbon atoms (e.g.,from 2 to 8 carbon atoms). Examples of alkynyl groups include ethynyl,propynyl, butynyl, pentynyl, and the like. The one or more carbon-carbontriple bonds can be internal (such as in 2-butyne) or terminal (such asin 1-butyne).

As used herein, “alkoxy” refers to an —O-alkyl group. Examples of alkoxygroups include methoxy, ethoxy, propoxy (e.g., n-propoxy andisopropoxy), t-butoxy groups, and the like. As used herein, “alkylthio”refers to an —S-alkyl group. Examples of alkylthio groups includemethylthio, ethylthio, propylthio (e.g., n-propylthio andisopropylthio), t-butylthio groups, and the like.

The term “carbalkoxy” refers to an alkoxycarbonyl group, where theattachment to the main chain is through the carbonyl group (C(O)).Examples include but are not limited to methoxy carbonyl, ethoxycarbonyl, and the like.

As used herein, “oxo” refers to a double-bonded oxygen (i.e., ═O). It isalso to be understood that the terminology C(O) refers to a —C═O group,whether it be ketone, aldehyde or acid or acid derivative. Similarly,S(O) refers to a —S═O group.

As used herein, “haloalkyl” refers to an alkyl group having one or morehalogen substituents. In some embodiments, a haloalkyl group can have 1to 10 carbon atoms (e.g., from 1 to 8 carbon atoms). Examples ofhaloalkyl groups include CF₃, C₂F₅, CHF₂, CH₂F, CCl₃, CHCl₂, CH₂Cl,C₂Cl₅, and the like. Perhaloalkyl groups, i.e., alkyl groups wherein allof the hydrogen atoms are replaced with halogen atoms (e.g., CF₃ andC₂F₅), are included within the definition of “haloalkyl.” For example, aC₁₋₁₀ haloalkyl group can have the formula —C_(i)H_(2i+1−j)X_(j),wherein X is F, Cl, Br, or I, i is an integer in the range of 1 to 10,and j is an integer in the range of 0 to 21, provided that j is lessthan or equal to 2i+1.

As used herein, when an alkyl group is followed by a functional group,such as alkylOH, it is recognized that it refers to an alkyl grouphaving one or more of the functional group substituents, which may belocated at any location on the alkyl chain. Example of C₁₋₈ alkylOHgroups include without limitation, CH₂OH, CH₂CH₂OH, C(CH₃)(CH₃)OH,C(CH₃)(CH₂OH)OH, and the like.

As used herein, “cycloalkyl” refers to a non-aromatic carbocyclic groupincluding cyclized alkyl, alkenyl, and alkynyl groups. A cycloalkylgroup can be monocyclic (e.g., cyclohexyl) or polycyclic (e.g.,containing fused, bridged, and/or spiro ring systems), wherein thecarbon atoms are located inside or outside of the ring system. Acycloalkyl group, as a whole, can have from 3 to 14 ring atoms (e.g.,from 3 to 8 carbon atoms for a monocyclic cycloalkyl group and from 7 to14 carbon atoms for a polycyclic cycloalkyl group). Any suitable ringposition of the cycloalkyl group can be covalently linked to the definedchemical structure. Examples of cycloalkyl groups include cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclopentenyl,cyclohexenyl, cyclohexadienyl, cycloheptatrienyl, norbornyl, norpinyl,norcaryl, adamantyl, and spiro[4.5]decanyl groups, as well as theirhomologs, isomers, and the like.

As used herein, “heteroatom” refers to an atom of any element other thancarbon or hydrogen and includes, for example, nitrogen, oxygen, sulfur,phosphorus, and selenium. As used herein, “cycloheteroalkyl” refers to anon-aromatic cycloalkyl group that contains at least one (e.g., one,two, three, four, or five) ring heteroatom selected from O, N, and S,and optionally contains one or more (e.g., one, two, or three) double ortriple bonds. A cycloheteroalkyl group, as a whole, can have from 3 to14 ring atoms and contains from 1 to 5 ring heteroatoms (e.g., from 3-6ring atoms for a monocyclic cycloheteroalkyl group and from 7 to 14 ringatoms for a polycyclic cycloheteroalkyl group). The cycloheteroalkylgroup can be covalently attached to the defined chemical structure atany heteroatom(s) or carbon atom(s) that results in a stable structure.One or more N or S atoms in a cycloheteroalkyl ring may be oxidized(e.g., morpholine N-oxide, thiomorpholine S-oxide, thiomorpholineS,S-dioxide). Cycloheteroalkyl groups can also contain one or more oxogroups, such as phthalimidyl, piperidonyl, oxazolidinonyl,2,4(1H,3H)-dioxo-pyrimidinyl, pyridin-2(1H)-onyl, and the like. Examplesof cycloheteroalkyl groups include, among others, morpholinyl,thiomorpholinyl, pyranyl, imidazolidinyl, imidazolinyl, oxazolidinyl,pyrazolidinyl, pyrazolinyl, pyrrolidinyl, pyrrolinyl, tetrahydrofuranyl,tetrahydrothienyl, piperidinyl, piperazinyl, and the like.

As used herein, “aryl” refers to an aromatic monocyclic hydrocarbon ringsystem or a polycyclic ring system where at least one of the rings inthe ring system is an aromatic hydrocarbon ring and any other aromaticrings in the ring system include only hydrocarbons. In some embodiments,a monocyclic aryl group can have from 6 to 14 carbon atoms and apolycyclic aryl group can have from 8 to 14 carbon atoms. The aryl groupcan be covalently attached to the defined chemical structure at anycarbon atom(s) that result in a stable structure. In some embodiments,an aryl group can have only aromatic carbocyclic rings, e.g., phenyl,1-naphthyl, 2-naphthyl, anthracenyl, phenanthrenyl groups, and the like.In other embodiments, an aryl group can be a polycyclic ring system inwhich at least one aromatic carbocyclic ring is fused (i.e., having abond in common with) to one or more cycloalkyl or cycloheteroalkylrings. Examples of such aryl groups include, among others, benzoderivatives of cyclopentane (i.e., an indanyl group, which is a5,6-bicyclic cycloalkyl/aromatic ring system), cyclohexane (i.e., atetrahydronaphthyl group, which is a 6,6-bicyclic cycloalkyl/aromaticring system), imidazoline (i.e., a benzimidazolinyl group, which is a5,6-bicyclic cycloheteroalkyl/aromatic ring system), and pyran (i.e., achromenyl group, which is a 6,6-bicyclic cycloheteroalkyl/aromatic ringsystem). Other examples of aryl groups include benzodioxanyl,benzodioxolyl, chromanyl, indolinyl groups, and the like.

As used herein, “heteroaryl” refers to an aromatic monocyclic ringsystem containing at least one ring heteroatom selected from O, N, and Sor a polycyclic ring system where at least one of the rings in the ringsystem is aromatic and contains at least one ring heteroatom. Aheteroaryl group, as a whole, can have from 5 to 14 ring atoms andcontain 1-5 ring heteroatoms. In some embodiments, heteroaryl groups caninclude monocyclic heteroaryl rings fused to one or more aromaticcarbocyclic rings, non-aromatic carbocyclic rings, or non-aromaticcycloheteroalkyl rings. The heteroaryl group can be covalently attachedto the defined chemical structure at any heteroatom or carbon atom thatresults in a stable structure. Generally, heteroaryl rings do notcontain O—O, S—S, or S—O bonds. However, one or more N or S atoms in aheteroaryl group can be oxidized (e.g., pyridine N-oxide, thiopheneS-oxide, thiophene S,S-dioxide). Examples of such heteroaryl ringsinclude pyrrolyl, furyl, thienyl, pyridyl, pyrimidyl, pyridazinyl,pyrazinyl, triazolyl, tetrazolyl, pyrazolyl, imidazolyl, isothiazolyl,thiazolyl, thiadiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, indolyl,isoindolyl, benzofuryl, benzothienyl, quinolyl, 2-methylquinolyl,isoquinolyl, quinoxalyl, quinazolyl, benzotriazolyl, benzimidazolyl,benzothiazolyl, benzisothiazolyl, benzisoxazolyl, benzoxadiazolyl,benzoxazolyl, cinnolinyl, 1H-indazolyl, 2H-indazolyl, indolizinyl,isobenzofuyl, naphthyridinyl, phthalazinyl, pteridinyl, purinyl,oxazolopyridinyl, thiazolopyridinyl, imidazopyridinyl, furopyridinyl,thienopyridinyl, pyridopyrimidinyl, pyridopyrazinyl, pyridopyridazinyl,thienothiazolyl, thienoxazolyl, thienoimidazolyl groups, and the like.Further examples of heteroaryl groups include 4,5,6,7-tetrahydroindolyl,tetrahydroquinolinyl, benzothienopyridinyl, benzofuropyridinyl groups,and the like.

As defined herein the term “lower alkyl”, when used alone or incombination refers to alkyl containing 1-6 carbon atoms. The alkyl groupmay be branched or straight-chained, and is as defined hereinabove.

The term “lower alkenyl” refers to a alkenyl group which contains 2-6carbon atoms. An alkenyl group is a hydrocarbyl group containing atleast one carbon-carbon double bond. As defined herein, it may beunsubstituted or substituted with the substituents described herein. Thecarbon-carbon double bonds may be between any two carbon atoms of thealkenyl group. It is preferred that it contains 1 or 2 carbon-carbondouble bonds and more preferably one carbon-carbon double bond. Thealkenyl group may be straight chained or branched. Examples include butare not limited to ethenyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 2-methyl-1-propenyl, 1,3-butadienyl, and the like.

The term “lower alkynyl”, as used herein, refers to an alkynyl groupcontaining 2-6 carbon atoms. An alkynyl group is a hydrocarbyl groupcontaining at least one carbon-carbon triple bond. The carbon-carbontriple bond may be between any two carbon atom of the alkynyl group. Inan embodiment, the alkynyl group contains 1 or 2 carbon-carbon triplebonds and more preferably one carbon-carbon triple bond. The alkynylgroup may be straight chained or branched. Examples include but are notlimited to ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl and thelike.

The present invention includes all pharmaceutically acceptableisotopically-labeled compounds of the invention, i.e. compounds offormula (I), wherein one or more atoms are replaced by atoms having thesame atomic number, but an atomic mass or mass number different from theatomic mass or mass number usually found in nature.

Examples of isotopes suitable for inclusion in the compounds of theinvention comprises isotopes of hydrogen, such as ²H and ³H, carbon,such as ¹¹C, ¹³C and ¹⁴C, chlorine, such as ³⁶CI, fluorine, such as ¹⁸F,iodine, such as ¹²³I and ¹²⁵I, nitrogen, such as ¹³N and ¹⁵N, oxygen,such as ¹⁵O, ¹⁷O and ¹⁸O, phosphorus, such as ³²P, and sulphur, such as³⁵S.

Certain isotopically-labelled compounds of formula (I), for example,those incorporating a radioactive isotope, are useful in drug and/orsubstrate tissue distribution studies. The radioactive isotopes tritium,i.e. ³H, and carbon-14, i.e. ¹⁴C, are particularly useful for thispurpose in view of their ease of incorporation and ready means ofdetection.

Substitution with heavier isotopes such as deuterium, i.e. ²H, mayafford certain therapeutic advantages resulting from greater metabolicstability, for example, increased in vivo half-life or reduced dosagerequirements, and hence may be preferred in some circumstances.

Substitution with positron emitting isotopes, such as ¹¹C, ¹⁸F, ¹⁵O and¹³N, can be useful in Positron Emission Topography (PET) studies forexamining substrate receptor occupancy.

Isotopically-labeled compounds of formula (I) can generally be preparedby conventional techniques known to those skilled in the art or byprocesses analogous to those described in the accompanying Examples andPreparations using an appropriate isotopically-labeled reagents in placeof the non-labeled reagent previously employed.

Pharmaceutically acceptable salts of any acidic compounds of theinvention are salts formed with bases, namely cationic salts such asalkali and alkaline earth metal salts, such as sodium, lithium,potassium, calcium, magnesium, as well as ammonium salts, such asammonium, trimethylammonium, diethylammonium, andtris-(hydroxymethyl)-methylammonium salts.

Similarly acid addition salts, such as of mineral acids, organiccarboxylic, and organic sulfonic acids e.g., hydrochloric acid,methanesulfonic acid, maleic acid, are possible provided a basic group,such as amino or pyridyl, constitutes part of the structure.

The present invention relates to the discovery that signal transductionpathways regulated by Hh and/or Smo can be modulated by the compounds ofthe invention.

In one embodiment, the compounds and methods of the present inventioncomprise compounds of formula (I) for inhibiting Smo-dependent pathwayactivation. Another aspect of the present invention includes compoundsand methods for inhibiting Hedgehog (ligand)-independent pathwayactivation. In certain embodiments, the present compounds and methodscan be used to counteract the phenotypic effects of unwanted activationof a Hedgehog pathway, such as resulting from Hedgehog gain-of-function,Ptc loss-of-function or smoothened gain-of-function mutations. Forinstance, the subject compounds and method can involve contacting a cell(in vitro or in vivo) with a Smo antagonist, such as a compound ofFormula (I) in an amount sufficient to antagonize a smoothened-dependentand/or Hedgehog independent activation pathway.

In one embodiment, the compounds of the invention (e.g., compounds ofFormula I) inhibit Hh signaling by locking the three dimensionalstructure of the Smo protein in an inactive conformation or preventingSmo from adopting an active conformation. In another embodiment, thecompounds of the invention (e.g., compounds of Formula I) inhibit Hhsignaling by preventing endogenous activating ligands for Smo frombinding to or activating Smo (i.e., acting via negative cooperativitywith endogenous agonists). In another embodiment, the compounds of theinvention (e.g., compounds of Formula I) inhibit Hh signaling byincreasing binding of endogenous inactivating ligands for Smo frombinding to or inactivating Smo (i.e., acting via positive cooperativitywith endogeous antagonist).

In another embodiment, the compounds of the invention (e.g., compoundsof Formula I) inhibit Hh signaling by preventing Smo from localizing tothe plasma membrane. In another embodiment, the compounds of theinvention (e.g., compounds of Formula I) inhibit Hh signaling bypreventing signaling from Ptch to Smo, in the presence or absence of Hhligand. In another embodiment, the compounds of the invention (e.g.,compounds of Formula I) inhibit Hh signaling by preventing thestabilization of Smo. In another embodiment, the compounds of theinvention (e.g., compounds of Formula I) inhibit Hh signaling bypreventing the phosphorylation of Smo on activating sites. In anotherembodiment, the compounds of the invention (e.g., compounds of FormulaI) inhibit Hh signaling by increasing the phosphorylation of Smo oninhibitory sites.

In still another embodiment, the compounds of the invention (e.g.,compounds of Formula I) inhibit Hh signaling by preventing Smo fromactivating downstream targets, such as transcription factor Gli. Inanother embodiment, the compounds of the invention (e.g., compounds ofFormula I) inhibit Hh signaling by effecting the inactivation,sequestration, and/or degradation of Smo.

In another embodiment, the methods of the present invention may be usedto regulate proliferation and/or differentiation of cells in vitroand/or in vivo, e.g., in the formation of tissue from stein cells, or toprevent the growth of hyperproliferative cells. In another particularembodiment, contacting the cell with—or introducing into the cell—acompound of the invention (e.g., a compound of Formula I) results ininhibition of cellular proliferation, inhibition of cancer/tumor cellgrowth and/or survival, and/or inhibition of tumorigenesis. Thus,another particular embodiment provides methods for inhibition and/orantagonism of the Hh pathway by employing compounds of the invention(e.g., a compound of Formula I) in a tumor cell.

In yet another embodiment, the methods of the present invention employcompounds of the invention (e.g., a compound of Formula I) as formulatedas a pharmaceutical preparation comprising a pharmaceutically acceptableexcipient or carrier, and said preparations may be administered to apatient to treat conditions involving unwanted cell proliferation suchas cancers and/or tumors (such as medulloblastoma, basal cell carcinoma,etc.), and non-malignant hyperproliferative disorders.

One embodiment of the present invention provides a method for inhibitingthe synthesis, expression, production, and/or activity of a Smo proteinin a cell in vitro or in vivo comprising, contacting said cell with, orintroducing into said cell, a compound of the invention (e.g., acompound of Formula I).

Another embodiment of the invention provides a method of diagnosing,preventing and/or treating cellular debilitations, derangements, and/ordysfunctions; hyperplastic, hyperproliferative and/or cancerous diseasestates; and/or metastasis of tumor cells, in a mammal characterized bythe presence and/or expression of a Smo gene or gene product (e.g., aSmo protein), comprising administering to a mammal a therapeuticallyeffective amount of an agent that inhibits or antagonizes the synthesisand/or expression and/or activity of a compound of the invention (e.g.,a compound of Formula I).

It is, therefore, specifically contemplated that compounds of Formula Iwhich interfere with aspects of Hh, Ptc, or smoothened signaltransduction activity will likewise be capable of inhibitingproliferation (or other biological consequences) in normal cells and/orcells having a patched loss-of-function phenotype, a Hedgehoggain-of-function phenotype, a smoothened gain-of-function phenotype or aGli gain-of-function phenotype. Thus, it is contemplated that in certainembodiments, these compounds may be useful for inhibiting Hedgehogactivity in normal cells, e.g., which do not have a genetic mutationthat activates the Hedgehog pathway. In preferred embodiments, thecompounds are capable of inhibiting at least some of the biologicalactivities of Hedgehog proteins, preferably specifically in targetcells.

Thus, the methods of the present invention include the use of compoundsof Formula I which agonize Ptc inhibition of Hedgehog signaling, such asby inhibiting activation of smoothened or downstream components of thesignal pathway, in the regulation of repair and/or functionalperformance of a wide range of cells, tissues and organs, includingnormal cells, tissues, and organs, as well as those having the phenotypeof Ptc loss-of-function, Hedgehog gain-of-function, smoothenedgain-of-function or Gli gain-of-function. For instance, the subjectmethod has therapeutic and cosmetic applications ranging from regulationof neural tissues, bone and cartilage formation and repair, regulationof spermatogenesis, regulation of benign prostate hyperplasia,regulation of blood vessel formation in wet macular degeneration,psoriasis, regulation of smooth muscle, regulation of lung, liver andother organs arising from the primitive gut, regulation of hematopoieticfunction, regulation of skin and hair growth, etc. Moreover, the subjectmethods can be performed on cells which are provided in culture (invitro), or on cells in a whole animal (in vivo).

In certain embodiments, a compound of Formula I can inhibit activationof a Hedgehog pathway by binding to smoothened or its downstreamproteins.

In another embodiment, the present invention provides the use ofpharmaceutical preparations comprising, as an active ingredient, aHedgehog signaling modulator such as a compound of Formula I, asmoothened antagonist such as described herein, formulated in all amountsufficient to inhibit, in vivo, proliferation or other biologicalconsequences of Ptc loss-of-function, Hedgehog gain-of-function,smoothened gain-of-function or Gli gain-of-function.

The treatment of subjects by administering compounds of the invention(e.g., compounds of Formula I) can be effective for both human andanimal subjects. Animal subjects to which the invention is applicableextend to both domestic animals and livestock, raised either as pets orfor commercial purposes. Examples are dogs, cats, cattle, horses, sheep,hogs, goats, and llamas.

The present invention also makes available methods and compounds forinhibiting activation of the Hedgehog signaling pathway, e.g., toinhibit normal but undesired growth states, for example benign prostatehyperplasia or blood vessel formation in wet macular degeneration,resulting from physiological activation of the Hedgehog signalingpathway, comprising contacting the cell with a compound of Formula I, ina sufficient amount to antagonize smoothened activity, or antagonize Gliactivity, e.g., to reverse or control the normal growth state.

The present invention makes available methods and compounds forinhibiting activation of the hedgehog signaling pathway, e.g., toinhibit aberrant growth states resulting from phenotypes such as Ptcloss-of-function, hedgehog gain-of-function, smoothened gain-of-functionor Gli gain-of-function, comprising contacting the cell with a compoundof Formula I, in a sufficient amount to agonize a normal Ptc activity,antagonize a normal hedgehog activity, antagonize smoothened activity,or antagonize Gli activity e.g., to reverse or control the aberrantgrowth state.

Members of the Hedgehog family of signaling molecules mediate manyimportant short- and long-range patterning processes during vertebratedevelopment. Pattern formation is the activity by which embryonic cellsform ordered spatial arrangements of differentiated tissues. Thephysical complexity of higher organisms arises during embryogenesisthrough the interplay of cell-intrinsic lineage and cell-extrinsicsignaling. Inductive interactions are essential to embryonic patterningin vertebrate development from the earliest establishment of the bodyplan, to the patterning of the organ systems, to the generation ofdiverse cell types during tissue differentiation. The effects ofdevelopmental cell interactions are varied: responding cells arediverted from one route of cell differentiation to another by inducingcells that differ from both the uninduced and induced states of theresponding cells (inductions). Sometimes cells induce their neighbors todifferentiate like themselves (homeogenetic induction); in other cases acell inhibits its neighbors from differentiating like itself. Cellinteractions in early development may be sequential, such that aninitial induction between two cell types leads to a progressiveamplification of diversity. Moreover, inductive interactions occur notonly in embryos, but in adult cells as well, and can act to establishand maintain morphogenetic patterns as well as induce differentiation.

The vertebrate family of hedgehog genes includes three members thatexist in mammals, known as Desert (Dhh), Sonic (Shh) and Indian (Ihh)hedgehogs, all of which encode secreted proteins. These various Hedgehogproteins consist of a signal peptide, a highly conserved N-terminalregion, and a more divergent C-terminal domain. Biochemical studies haveshown that autoproteolytic cleavage of the Hh precursor protein proceedsthrough an internal thioester intermediate which subsequently is cleavedin a nucleophilic substitution. It is likely that the nucleophile is asmall lipophilic molecule which becomes covalently bound to theC-terminal end of the N-peptide, tethering it to the cell surface. Thebiological implications are profound. As a result of the tethering, ahigh local concentration of N-terminal Hedgehog peptide is generated onthe surface of the Hedgehog producing cells. It is this N-terminalpeptide which is both necessary and sufficient for short- and long-rangeHedgehog signaling activities.

Smoothened (Smo) encodes a 1024 amino acid transmembrane protein thatacts as a transducer of the Hedgehog (Hh) signal. Smo protein has 7hydrophobic membrane-spanning domains, an extracellular amino-terminalregion, and an intracellular carboxy-terminal region. Smo bears somesimilarity to G protein-coupled receptors and is most homologous to theFrizzled (Fz) family of serpentine proteins. (Alcedo et al. (1996) Cell86: 221)

An inactive Hedgehog signaling pathway is where the transmembraneprotein receptor Patched (Ptc) inhibits the activity of Smoothened(Smo), a seven transmembrane protein. The transcription factor Gli, adownstream component of Hh signaling, is prevented from entering thenucleus through interactions with cytoplasmic proteins, including Fusedand Suppressor of fused (Sufu). As a consequence, transcriptionalactivation of Hedgehog target genes is repressed. Activation of thepathway is initiated through binding of any of the three mammalianligands (Dhh, Shh or Ihh) to Ptc. Ligand binding results in a reversalof the repression of Smo, thereby activating a cascade that leads to thetranslocation of the active form of the transcription factor Gli to thenucleus. Nuclear Gli activates target gene expression, including Ptc andGli itself.

Ligand binding by Hh alters the interaction of Smo and Ptc, reversingthe repression of Smo, whereupon Smo moves from internal structureswithin the cell to the plasma membrane. The localization of Smo to theplasma membrane triggers activation of Hh pathway target genes in anHh-independent manner. (Zhu et al. (2003) Genes Dev. 17(10):1240) Thecascade activated by Smo leads to the translocation of the active formof the transcription factor Gli to the nucleus. The activation of Smo,through translocated nuclear Gli, activates Hh pathway target geneexpression, including of Wnts, TGFβ, and Ptc and Gli themselves.

Increased levels of Hedgehog signaling are sufficient to initiate cancerformation and are required for tumor survival. These cancers include,but are not limited to, prostate cancer (“Hedgehog signalling inprostate regeneration, neoplasia and metastasis”, Karhadkar S S, Bova GS, Abdallah N, Dhara S, Gardner D, Maitra A, Isaacs J T, Berman D M,Beachy P A., Nature. 2004 Oct. 7; 431(7009):707-12; “Inhibition ofprostate cancer proliferation by interference with SONIC HEDGEHOG-GLI1signaling”, Sanchez P, Hernandez A M, Stecca B, Kahler A J, DeGueme A M,Barrett A, Beyna M, Datta M W, Datta S, Ruiz i Altaba A., Proc Natl AcadSci USA. 2004 Aug. 24; 101(34):12561-6), (“Cytotoxic effects induced bya combination of cyclopamine and gefitinib, the selective hedgehog andepidermal growth factor receptor signaling inhibitors, in prostatecancer cells,” Mimeault M, Moore E, Moniaux N, et al (2006),International Journal of Cancer; 118 (4):1022-31) breast cancer(“Hedgehog signaling pathway is a new therapeutic target for patientswith breast cancer”, Kubo M, Nakamura M, Tasaki A, Yamanaka N, NakashimaH, Nomura M, Kuroki S, Katano M., Cancer Res. 2004 Sep. 1;64(17):6071-4), (“Hedgehog signaling and Bmi-1 regulate self-renewal ofnormal and malignant human mammary stem cells,” Liu S, Dontu G, Mantle ID, et al (2006) Cancer Res; 66 (12):6063-71), (“Constitutive activationof smoothened (SMO) in mammary glands of transgenic mice leads toincreased proliferation, altered differentiation and ductal dysplasia,”Moraes R C, Zhang N M, Harrington N, et al (2007), Development; 134(6):1231-42), medulloblastoma (“Medulloblastoma growth inhibition byhedgehog pathway blockade”, Berman D M, Karhadkar S S, Hallahan A R,Pritchard J I, Eberhart C G, Watkins D N, Chen J K, Cooper M K, TaipaleJ, Olson J M, Beachy P A., Science. 2002 Aug. 30; 297(5586):1559-61),non-melanoma skin cancer, i.e. squamous cell carcinoma (SCC) and basalcell carcinoma (BCC) (“Identification of a small molecule inhibitor ofthe hedgehog signaling pathway: effects on basal cell carcinoma-likelesions”, Williams J A, Guicherit O M, Zaharian B I, Nu Y, Chai L,Wichterle H, Kon C, Gatchalian C, Porter J A, Rubin L L, Wang F Y., ProcNatl Acad Sci USA. 2003 Apr. 15; 100(8):4616-21; “Activating Smoothenedmutations in sporadic basal-cell carcinoma”, Xie J, Murone M, Luoh S M,Ryan A, Gu Q, Zhang C, Bonifas J M, Lam C W, Hynes Ni, Goddard A,Rosenthal A, Epstein E H Jr, de Sauvage F J., Nature. 1998 Jan. 1;391(6662):90-2), pancreatic, esophagus, stomach, and billary cancers(“Hedgehog is an early and late mediator of pancreatic cancertumorigenesis”, Thayer S P, di Magliano M P, Heiser P W, Nielsen C M,Roberts D J, Lauwers G Y, Qi Y P, Gysin S, Fernandez-del Castillo C,Yajnik V, Antoniu B, McMahon M, Warshaw A L, Hebrok M., Nature. 2003Oct. 23; 425(6960):851-6; “Widespread requirement for Hedgehog ligandstimulation in growth of digestive tract tumours”, Berman D M, KarhadkarS S, Maitra A, Montes De Oca R, Gerstenblith M R, Briggs K, Parker A R,Shimada Y, Eshleman J R, Watkins D N, Beachy P A., Nature. 2003 Oct. 23;425(6960):846-51), (“Nuclear factor-kappa B contributes to hedgehogsignaling pathway activation through sonic hedgehog induction inpancreatic cancer,” Nakashima H, Nakamura M, Yamaguchi H, et al (2006),Cancer Research; 66 (14):7041-9), (“Blockade of hedgehog signalinginhibits pancreatic cancer invasion and metastases: A new paradigm forcombination therapy in solid cancers,” Feldmann G, Dhara S, Fendrich V,et al (2007) Cancer Research; 67 (5):2187-96), (“Oncogenic KRASsuppresses Gli1 degradation and activates Hedgehog signaling pathway inpancreatic cancer cells,” Ji Z, Mei F C, Xie J, et al (2007), J BiolChem; 282 (19):14048-55), and small-cell lung cancer (“Hedgehogsignalling within airway epithelial progenitors and in small-cell lungcancer”, Watkins D N, Berman D M, Burkholder S G, Wang B, Beachy P A,Baylin S B., Nature. 2003 Mar. 20; 422(6929):313-7), (“Hedgehogsignaling in small-cell lung cancer: Frequent in vivo but a rare eventin vitro,” Vestergaard J, Pedersen M W, Pedersen N, et al (2006), LungCancer; 52 (3):281-90).

Additional cancers in which increased levels of Hedgehog signaling aresufficient to initiate cancer formation and are required for tumorsurvival include, but are not limited to colon cancer (“SonicHedgehog-dependent proliferation in a series of patients with colorectalcancer,” Douard R, Moutereau S, Pernet P, et al (2006) Surgery; 139(5):665-70), (“Hedgehog signalling in colorectal tumour cells: Inductionof apoptosis with cyclopamine treatment,” Qualtrough D, Buda A, GaffieldW, et al (2004), International Journal of Cancer; 110 (6):831-7),glioma, (“Cyclopamine-mediated Hedgehog pathway inhibition depletesstem-like cancer cells in glioblastoma,” Bar E E, Chaudhry A, Lin A, etal, Neuro-Oncology; 2007, 9 (4):594), (“HEDGEHOG-GLI1 signalingregulates human glioma growth, cancer stem cell self-renewal, andtumorigenicity,” Clement V, Sanchez P, de Tribolet N, et al, (2007)Current Biology 17 (2):165-72), (“Ligand-dependent activation of thehedgehog pathway in glioma progenitor cells,” Ehteshan M, Sarangi A,Valadez J G, et al (2007) Oncogene; Mar. 12, 2007, Epub ahead of print),melanoma (“Melanomas require HEDGEHOG-GLI signaling reaulated byinteractions between GLI1 and the RAS-MEK/AKT pathways,” Stecca B, MasC, Clement V, et al (2007), Proceedings of the National Academy ofSciences of the United States of America; 104 (14):5895-900), non smallcell lung cancer (NSCLC) (“Frequent requirement of hedgehog signaling innon-small cell lung carcinoma,” Yuan Z, Goetz J A, Singh S, et al(2007), Oncogene; 26 (7):1046-55), ovarian, (“Hedgehog signal pathway isactivated in ovarian carcinomas, correlating with cell proliferation:It's inhibition leads to growth suppression and apoptosis,” Chen X J,Horiuchi A, Kikuchi N, et al, Cancer Science; (2007) 98 (1):68-76),liver (“Activation of the hedgehog pathway in human hepatocellularcarcinomas,” Huang S H, He J, Zhang X L, et al (2006), Carcinogenesis;27 (7):1334-40), (“Dysregulation of the Hedgehog pathway in humanhepatocarcinogenesis,” Sicklick J K, Li Y X, Jayaraman A, et al (2006),Carcinogenesis; 27 (4):748-57), renal (“Clear cell sarcoma of thekidney: Up-regulation of neural markers with activation of the sonichedgehog and Akt pathways,” Cutcliffe C, Kersey D, Huang C C, et al(2005), Clinical Cancer Research; 11 (22):7986-94), Rhabdomyosarcoma,(“Rhabdomyosarcomas and radiation hypersensitivity in a mouse model ofGorlin syndrome,” Hahn H, Wojnowski L, Zimmer A M, et al (1998), NatureMedicine; 4 (5):619-22), (“Deregulation of the hedgehog signallingpathway: a possible role for the PTCH and SUFU genes in humanrhabdomyoma and rhabdomyosarcoma development,” Tostar U, Maim C J,Meis-Kindblom J M, et al (2006), Journal of Pathology; 208 (1):17-25),and Chondrosarcoma (“Constitutive hedgehog signaling in chondrosarcomaup-regulates tumor cell proliferation,” Tiet T D, Hopyan S, Nadesan P,et al (2006), American Journal of Pathology; 168 (1):321-30).

Hedgehog pathway inhibitors (e.g. cyclopamine) have been shown to beuseful in the treatment of psoriasis (“Cyclopamine: inhibiting hedgehogin the treatment of psoriasis” Cutis, 2006, 78(3):185-8; Br. J.Dermatology, 2006 April; 154(4):619-23, “Psoriatic skin expresses thetranscription factor Gli1: possible contribution of decreasedneurofibromin expression”, Endo H, Momota Y, Oikawa A, Shinkai H.).

Malignant lymphoma (ML) involves the cells of the lymphatic system, andis the fifth most common cancer in the U.S. ML includes Hodgkin'sdisease, and non-Hodgkin's diseases which are a heterogeneous group oflymphoid proliferative diseases. Hodgkin's disease accounts forapproximately 14% of all malignant lymphomas. The non-Hodgkin'slymphomas are a diverse group of malignancies that are predominately ofB-cell origin. In the Working Formulation classification scheme, theselymphomas been divided into low-, intermediate-, and high-gradecategories by virtue of their natural histories (see “The Non-Hodgkin'sLymphoma Pathologic Classification Project,” Cancer 49:2112-2135, 1982).The low-grade lymphomas are indolent, with a median survival of 5 to 10years (Horning and Rosenberg, N. Engl. J. Med. 311:1471-1475, 1984).Although chemotherapy can induce remissions in the majority of indolentlymphomas, cures are rare and most patients eventually relapse,requiring further therapy. The intermediate- and high-grade lymphomasare more aggressive tumors, but they have a greater chance for cure withchemotherapy. However, a significant proportion of these patients willrelapse and require further treatment.

Multiple myeloma (MM) is malignant tumor composed of plasma cells of thetype normally found in the bone marrow. These malignant plasma cellsaccumulate in bone marrow and typically produce monoclonal IgG or IgAmolecules. The malignant plasma cells home to and expand in the bonemarrow causing anemia and immunosuppression due to loss of normalhematopoiesis. Individuals suffering from multiple myeloma oftenexperience anemia, osteolytic lesions, renal failure, hypercalcemia, andrecurrent bacterial infections. MM represents the second most commonhematopoietic malignancy.

The present invention is predicated in part on the discoveries by thepresent inventors that lymphoma and multiple myeloma diseases aredependent on the hedgehog (Hh) signaling pathway using lymphoma andplasmacytoma cells isolated from transgenic Eμ-Myc mice and Cdkn2aknockout mice, and discovering that hedgehog ligands mediate theinteraction between stroma and lymphoma cells. The same was found forlymphoma and multiple myeloma samples isolated from patient samples fromthe bone (multiple myeloma) or from lymph nodes, bone marrow or spleensfrom non-Hodgkin's lymphoma (NHL) patients and also for chroniclymphocytic leukemia (CLL) samples. In addition, it was found thatinhibition of the Hh signaling pathway induces apoptosis of stromadependent lymphoma cells, and that overexpression of hedgehog pathwaymembers inhibit cyclopamine induced apoptosis of lymphoma cells invitro. Further, the inventors found that treating mice with hedgehogpathway inhibitors abrogates lymphoma expansion in vivo. Finally, theinventors discovered that there is no expression of Gli3 in spleenB-cells and in the majority of cyclopamine responsive lymphomas, but apredominant expression in all cyclopamine resistant lymphomas.

These data indicate that Hh signaling provides an importantanti-apoptotic signal for the initial steps of transformation by c-Mycand plays an important role for lymphoma maintenance. Thus, disruptionof the Hh signaling pathway provides novel means for treating lymphomas(e.g., NHL), multiple myelomas, CLL and other hematopoieticmalignancies. In addition, expression of Gli3 in lymphomas provides anegative predictive factor for responsiveness to Hh inhibition and animportant means for patient stratification.

In accordance with these discoveries, the invention provides methods forinhibiting growth of tumor cells, e.g., lymphoma and myeloma cells. Theinvention provides methods and compositions to treat lymphoma or myelomain a subject by inhibiting growth of tumor cells. The methods are alsouseful to prevent tumorigenesis in a subject. Some of the methods aredirected to treating lymphomas which do not have significant expressionof Gli3 relative to spleen B cells. The methods involve administering tothe subject in need of treatment a pharmaceutical composition thatcontains an antagonizing agent of Hh signaling (e.g., a compound ofFormula I). Compound of the invention down-regulate cellular level orinhibit a biological activity of an Hh signaling pathway member.

This invention provides methods of prophylactic or therapeutic treatmentof cancers of the blood and lymphatic systems, including lymphomas,leukemia, and myelomas. The methods employ an antagonist of hedgehogsignaling pathway to inhibit growth and proliferation of lymphoma cells,leukemia cells, or myeloma cells. Lymphoma is malignant tumor oflymphoblasts derived from B lymphocytes. Myeloma is a malignant tumorcomposed of plasma cells of the type normally found in the bone marrow.Leukemia is an acute or chronic disease that involves the blood formingorgans. NHLs are characterized by an abnormal increase in the number ofleucocytes in the tissues of the body with or without a correspondingincrease of those in the circulating blood and are classified accordingto the type of leucocyte most prominently involved.

By way of example, subjects suffering from or at risk of development oflymphoma (e.g., e.g., B-cell lymphoma, plasmoblastoma, plasmacytoma orCLL) can be treated with methods of the invention. Preferably, thesubject is a human being. The methods entail administering to thesubject a pharmaceutical composition containing an effective amount of acompound of Formula I to inhibit the hedgehog signaling pathway. Thesubject can be one who is diagnosed with lymphoma, with or withoutmetastasis, at any stage of the disease (e.g., stage I to IV, Ann ArborStaging System). Lymphomas suitable for treatment with methods of theinvention include but are not limited to Hodgkin's disease andnon-Hodgkin's disease. Hodgkin's disease is a human malignant disorderof lymph tissue (lymphoma) that appears to originate in a particularlymph node and later spreads to the spleen, liver and bone marrow. Itoccurs mostly in individuals between the ages of 15 and 35. It ischaracterized by progressive, painless enlargement of the lymph nodes,spleen and general lymph tissue. Classic Hodgkin's disease is dividedinto four subtypes: (1) nodular sclerosis Hodgkin's disease (NSHD); (2)mixed cellularity Hodgkin's disease (MCHD); (3) lymphocyte depletionHodgkin's disease (LDHD); and (4) lymphocyte-rich classic Hodgkin'sdisease (cLRHD).

In some preferred embodiments, the present methods are used to treatnon-Hodgkin's Lymphoma (NHL). Non-Hodgkin's disease is also calledlymphosarcoma and refers to a group of lymphomas which differ inimportant ways from Hodgkin's disease and are classified according tothe microscopic appearance of the cancer cells. Non-Hodgkin's lymphomaincludes but is not limited to (1) slow-growing lymphomas and lymphoidleukemia (e.g., chronic lymphocytic leukemia, small lymphocyticleukemia, lymphoplasmacytoid lymphoma, follicle center lymphoma,follicular small cleaved cell, follicular mixed cell, marginal zoneB-cell lymphoma, hairy cell leukemia, plasmacytoma, myeloma, largegranular lymphocyte leukemia, mycosis fungoides, szary syndrome); (2)moderately aggressive lymphomas and lymphoid leukemia (e.g.,prolymphocytic leukemia, mantle cell lymphoma, follicle center lymphoma,follicular small cleaved cell, follicle center lymphoma, chroniclymphocytic leukemia/prolymphocytic leukemia, angiocentric lymphoma,angioimmunoblastic lymphoma); (3) aggressive lymphomas (e.g., largeB-cell lymphoma, peripheral T-cell lymphomas, intestinal T-celllymphoma, anaplastic large cell lymphoma); and (4) highly aggressivelymphomas and lymphoid leukemia (e.g., B-cell precursor B-lymphoblasticleukemia/lymphoma, Burkitt's lymphoma, high-grade B-cell lymphoma,Burkitt's-like T-cell precursor T-lymphoblastic leukemia/lymphoma). Themethods of the present invention can be used for adult or childhoodforms of lymphoma, as well as lymphomas at any stage, e.g., stage I, II,III, or IV. The methods described herein can also be employed to treatother forms of leukemia, e.g., acute lymphocytic leukemia (ALL).

Some of the therapeutic methods of the invention are particularlydirected to treating lymphomas or myelomas which do not express Gli3. Asdisclosed in the Examples below, it was observed that, while Gli1 andGli2 were expressed in all lymphomas, detectable Gli3 expression waspresent mainly in lymphomas which were resistant to Hh pathwayinhibition by cyclopamine. There is no expression of Gli3 in normalspleen B-cells and in the majority of cyclopamine responsive lymphomas.Thus, prior to treatment with Hh antagonists, subjects with lymphomascan be first examined for expression of Gli3 in a lymphoma cell sampleobtained from the subject. Gli3 expression level in the sample can becompared to Gli3 expression level in normal spleen B cells obtained fromthe subject. Gli3 expression levels in the lymphoma or myeloma samplesand the control cells can be determined using methods well known in theart, e.g., as described in the Examples below. A likely responsivenessto treatment with Hh antagonists described herein is indicated by thelack of detectable Gli3 expression in the lymphoma or myeloma samples oran expression level that is not significantly higher (e.g., not morethan 25%, 50%, or 100% higher) than Gli3 expression level in the normalB cell. Other than being an additional step of the therapeutic methodsof the invention, the pre-screening for lack of Gli3 expression can beused independently as a method for patient stratification.

In addition to lymphomas, the methods and compositions described aboveare also suitable for the treatment of myelomas. Multiple myeloma is afatal neoplasm characterized by an accumulation of a clone of plasmacells, frequently accompanied by the secretion of Ig chains. Bone marrowinvasion by the tumor is associated with anemia, hypogammaglobinemia,and granulocytopenia with concomitant bacterial infections. An abnormalcytokine environment, principally raised IL-6 and IL-1β levels, oftenresults in increased osteoclasis leading to bone pain, fractures, andhypercalcemia. Despite aggressive chemotherapy and transplantation,multiple myeloma is a universally fatal plasma proliferative disorder.

Compounds of the invention are useful in the treatment of hedgehogrelated disorders such as basal cell nevus syndrome (also calledGorlin's syndrome and/or nevoid basal cell carcinoma), a rare autosomaldominant cancer genetic syndrome.

Compounds of the invention are useful in the treatment of basal cellcarcinoma (BCC or rodent ulcer), tumors of the adrenal glands arisingfrom the cortex or the medulla part of the adrenal gland medulla, andovarian tumors.

Compounds of the invention are useful in the treatment of boneovergrowth disorders including, but are not limited to, acromegaly,macrocephaly, Sotos syndrome, progressive diaphyseal dysplasia (PDD orCamurati-Engelmann disease), craniodiaphyseal dysplasia, and endostealhyperostosis disorders including Van Buchem disease (types I and II) andsclerosteosis.

Compounds of the invention are useful in the treatment of unwanted hairgrowth, for example, hairy moles and cosmetic prevention of hairregrowth after epilation. Compounds of the invention are useful in thetreatment of Liver fibrosis.

Thus, the methods of the present invention include the use of compoundsof the invention which agonize Ptc inhibition of Hedgehog signaling,such as by inhibiting activation of smoothened or downstream componentsof the signal pathway, in the regulation of repair and/or functionalperformance of a wide range of cells, tissues and organs, includingnormal cells, tissues, and organs, as well as those having the phenotypeof Ptc loss-of-function, Hedgehog gain-of-function, smoothenedgain-of-function or Gli gain-of-function. For instance, the subjectmethod has therapeutic and cosmetic applications ranging from regulationof neural tissues, bone and cartilage formation and repair, regulationof spermatogenesis, regulation of benign prostate hyperplasia,regulation of blood vessel formation in wet macular degeneration,psoriasis, regulation of smooth muscle, regulation of lung, liver andother organs arising from the primitive gut, regulation of hematopoieticfunction, regulation of skin and hair growth, etc. Moreover, the subjectmethods can be performed on cells which are provided in culture (invitro), or on cells in a whole animal (in vivo).

In accordance with the foregoing, the present invention further providesa method for preventing or treating any of the diseases or disordersdescribed above in a subject in need of such treatment, which methodcomprises administering to said subject a therapeutically effectiveamount (See, “Administration and Pharmaceutical Compositions”, infra) ofa compound of Formula I or a pharmaceutically acceptable salt thereof.For any of the above uses, the required dosage will vary depending onthe mode of administration, the particular condition to be treated andthe effect desired.

Administration and Pharmaceutical Compositions

The invention relates to the use of pharmaceutical compositionscomprising compounds of Formula (I) in the therapeutic (and, in abroader aspect of the invention, prophylactic) treatment of aHedgehog-related disorder(s).

In general, compounds of the invention will be administered intherapeutically effective amounts via any of the usual and acceptablemodes known in the art, either singly or in combination with one or moretherapeutic agents. A therapeutically effective amount may vary widelydepending on the severity of the disease, the age and relative health ofthe subject, the potency of the compound used and other factors. Ingeneral, satisfactory results are indicated to be obtained systemicallyat daily dosages of from about 0.03 to 2.5 mg/kg per body weight. Anindicated daily dosage in the larger mammal, e.g. humans, is in therange from about 0.5 mg to about 100 mg, conveniently administered, e.g.in divided doses up to four times a day or in retard form. Suitable unitdosage forms for oral administration comprise from ca. 1 to 50 mg activeingredient.

Compounds of the invention can be administered as pharmaceuticalcompositions by any conventional route, in particular enterally, e.g.,orally, e.g., in the form of tablets or capsules, or parenterally, e.g.,in the form of injectable solutions or suspensions, topically, e.g., inthe form of lotions, gels, ointments or creams, or in a nasal orsuppository form. Pharmaceutical compositions comprising a compound ofthe present invention in free form or in a pharmaceutically acceptablesalt form in association with at least one pharmaceutically acceptablecarrier or diluent can be manufactured in a conventional manner bymixing, granulating or coating methods. For example, oral compositionscan be tablets or gelatin capsules comprising the active ingredienttogether with a) diluents, e.g., lactose, dextrose, sucrose, mannitol,sorbitol, cellulose and/or glycine; b) lubricants, e.g., silica, talcum,stearic acid, its magnesium or calcium salt and/or polyethyleneglycol;for tablets also c) binders, e.g., magnesium aluminum silicate, starchpaste, gelatin, tragacanth, methylcellulose, sodiumcarboxymethylcellulose and or polyvinylpyrrolidone; if desired d)disintegrants, e.g., starches, agar, alginic acid or its sodium salt, oreffervescent mixtures; and/or e) absorbents, colorants, flavors andsweeteners. Injectable compositions can be aqueous isotonic solutions orsuspensions, and suppositories can be prepared from fatty emulsions orsuspensions.

The compositions may be sterilized and/or contain adjuvants, such aspreserving, stabilizing, wetting or emulsifying agents, solutionpromoters, salts for regulating the osmotic pressure and/or buffers. Inaddition, they may also contain other therapeutically valuablesubstances. Suitable formulations for transdermal applications includean effective amount of a compound of the present invention with acarrier. A carrier can include absorbable pharmacologically acceptablesolvents to assist passage through the skin of the host. For example,transdermal devices are in the form of a bandage comprising a backingmember, a reservoir containing the compound optionally with carriers,optionally a rate controlling barrier to deliver the compound to theskin of the host at a controlled and predetermined rate over a prolongedperiod of time, and means to secure the device to the skin. Matrixtransdermal formulations may also be used. Suitable formulations fortopical application, e.g., to the skin and eyes, are preferably aqueoussolutions, ointments, creams or gels well-known in the art. Such maycontain solubilizers, stabilizers, tonicity enhancing agents, buffersand preservatives.

Compounds of the invention can be administered in therapeuticallyeffective amounts in combination with one or more therapeutic agents(pharmaceutical combinations). For example, synergistic effects canoccur with immunomodulatory, anti-inflammatory substances, otheranti-tumor therapeutic agents, chemotherapeutic agents, ablation orother therapeutic hormones, antineoplastic agents and/or monoclonalantibodies useful against lymphomas or myelomas. Some of the well knownanti-cancer drugs are described in the art, e.g., Cancer Therapeutics:Experimental and Clinical Agents, Teicher (Ed.), Humana Press (1^(st)ed., 1997); and Goodman and Gilman's The Pharmacological Basis ofTherapeutics, Hardman et al. (Eds.), McGraw-Hill Professional (10^(th)ed., 2001). Examples of suitable anti-cancer drugs include5-fluorouracil, vinblastine sulfate, estramustine phosphate, suramin andstrontium-89. Examples of suitable chemotherapeutic agents includeAsparaginase, Bleomycin Sulfate, Cisplatin, Cytarabine, FludarabinePhosphate, Mitomycin and Streptozocin.

Where the compounds of the invention are administered in conjunctionwith other therapies, dosages of the co-administered compounds will ofcourse vary depending on the type of co-drug employed, on the specificdrug employed, on the condition being treated and so forth.

An Hh inhibitor of the present invention may be usefully combined withanother pharmacologically active compound, or with two or more otherpharmacologically active compounds, particularly in the treatment ofcancer. For example, a compound of the formula (I), or apharmaceutically acceptable salt thereof, as defined above, may beadministered simultaneously, sequentially or separately in combinationwith one or more agents selected from chemotherapy agents, e.g. mitoticinhibitors such as a taxane, a vinca alkaloid, paclitaxel, docetaxel,vincristine, vinblastine, vinorelbine or vinflunine, and otheranticancer agents, e.g. cisplatin, 5-fluorouracil or5-fluoro-2-4(1H,3H)-pyrimidinedione (5FU), flutamide or gemcitabine.

Such combinations may offer significant advantages, includingsynergistic activity, in therapy. A compound of the formula (I) may alsobe used to advantage in combination with other antiproliferativecompounds. Such antiproliferative compounds include, but are not limitedto aromatase inhibitors; antiestrogens; topoisomerase I inhibitors;topoisomerase II inhibitors; microtubule active compounds; alkylatingcompounds; compounds which induce cell differentiation processes;cyclooxygenase inhibitors; MMP inhibitors; mTOR inhibitors;antineoplastic antimetabolites; platin compounds; compoundstargeting/decreasing a protein or lipid kinase activity and furtheranti-angiogenic compounds; compounds which target, decrease or inhibitthe activity of a protein or lipid phosphatase; gonadorelin agonists;anti-androgens; methionine aminopeptidase inhibitors; bisphosphonates;biological response modifiers; antiproliferative antibodies; heparanaseinhibitors; inhibitors of Ras oncogenic isoforms; telomerase inhibitors;proteasome inhibitors; compounds used in the treatment of hematologicmalignancies; compounds which target, decrease or inhibit the activityof Flt-3; Hsp90 inhibitors such as 17-AAG (17-allylamino-gelda-namycin,NSC330507), 17-DMAG(17-dimethylaminoethylamino-17-demethoxy-geldana-mycin, NSC707545),IPI-504, CNF1010, CNF2024, CNF1010 from Conforma Therapeutics;temozolomide (TEMODAL); kinesin spindle protein inhibitors, such asSB715992 or SB743921 from GlaxoSmithKline, or pentamidine/chlorpromazinefrom CombinatoRx; PI3K inhibitors; RAF inhibitors; EDG binders,antileukemia compounds, ribonucleotide reductase inhibitors,S-adenosylmethionine decarboxylase inhibitors, antiproliferativeanti-bodies or other chemotherapeutic compounds. Further, alternativelyor in addition they may be used in combination with other tumortreatment approaches, including surgery, ionizing radiation,photodynamic therapy, implants, e.g. with corticosteroids, hormones, orthey may be used as radiosensitizers. Also, in anti-inflammatory and/orantiproliferative treatment, combination with anti-inflammatory drugs isincluded. Combination is also possible with antihistamine drugsubstances, bronchodilatatory drugs, NSAID or antagonists of chemokinereceptors.

The invention also provides for a pharmaceutical combinations, e.g. akit, comprising a) a first agent which is a compound of the invention asdisclosed herein, in free form or in pharmaceutically acceptable saltform, and b) at least one co-agent. The kit can comprise instructionsfor its administration.

The terms “co-administration” or “combined administration” or the likeas utilized herein are meant to encompass administration of the selectedtherapeutic agents to a single patient, and are intended to includetreatment regimens in which the agents are not necessarily administeredby the same route of administration or at the same time.

The term “pharmaceutical combination” as used herein means a productthat results from the mixing or combining of more than one activeingredient and includes both fixed and non-fixed combinations of theactive ingredients. The term “fixed combination” means that the activeingredients, e.g. a compound of Formula I and a co-agent, are bothadministered to a patient simultaneously in the form of a single entityor dosage. The term “non-fixed combination” means that the activeingredients, e.g. a compound of Formula I and a co-agent, are bothadministered to a patient as separate entities either simultaneously,concurrently or sequentially with no specific time limits, wherein suchadministration provides therapeutically effective levels of the 2compounds in the body of the patient. The latter also applies tococktail therapy, e.g. the administration of 3 or more activeingredients.

Processes for Making Compounds of the Invention

Representative examples of synthesis of the compounds of the invention,e.g., compounds of Formula (I), can be found in the Examples section ofthe present application.

A compound of the invention can be prepared as a pharmaceuticallyacceptable acid addition salt by reacting the free base form of thecompound with a pharmaceutically acceptable inorganic or organic acid.Alternatively, a pharmaceutically acceptable base addition salt of acompound of the invention can be prepared by reacting the free acid formof the compound with a pharmaceutically acceptable inorganic or organicbase.

Alternatively, the salt forms of the compounds of the invention can beprepared using salts of the starting materials or intermediates.

The free acid or free base forms of the compounds of the invention canbe prepared from the corresponding base addition salt or acid additionsalt from, respectively. For example a compound of the invention in anacid addition salt form can be converted to the corresponding free baseby treating with a suitable base (e.g., ammonium hydroxide solution,sodium hydroxide, and the like). A compound of the invention in a baseaddition salt form can be converted to the corresponding free acid bytreating with a suitable acid (e.g., hydrochloric acid, etc.).

Prodrug derivatives of the compounds of the invention can be prepared bymethods known to those of ordinary skill in the art (e.g., for furtherdetails see Saulnier et al., (1994), Bioorganic and Medicinal ChemistryLetters, Vol. 4, p. 1985).

Protected derivatives of the compounds of the invention can be made bymeans known to those of ordinary skill in the art. A detaileddescription of techniques applicable to the creation of protectinggroups and their removal can be found in T. W. Greene, “ProtectingGroups in Organic Chemistry”, 3^(rd) edition, John Wiley and Sons, Inc.,1999.

Compounds of the present invention can be conveniently prepared, orformed during the process of the invention, as solvates (e.g.,hydrates). Hydrates of compounds of the present invention can beconveniently prepared by recrystallization from an aqueous/organicsolvent mixture, using organic solvents such as dioxin, tetrahydrofuranor methanol.

Compounds of the invention can be prepared as their individualstereoisomers by reacting a racemic mixture of the compound with anoptically active resolving agent to form a pair of diastereoisomericcompounds, separating the diastereomers and recovering the opticallypure enantiomers. While resolution of enantiomers can be carried outusing covalent diastereomeric derivatives of the compounds of theinvention, dissociable complexes are preferred (e.g., crystallinediastereomeric salts). Diastereomers have distinct physical properties(e.g., melting points, boiling points, solubilities, reactivity, etc.)and can be readily separated by taking advantage of thesedissimilarities. The diastereomers can be separated by chromatography,or preferably, by separation/resolution techniques based upondifferences in solubility. The optically pure enantiomer is thenrecovered, along with the resolving agent, by any practical means thatwould not result in racemization. A more detailed description of thetechniques applicable to the resolution of stereoisomers of compoundsfrom their racemic mixture can be found in Jean Jacques, Andre Collet,Samuel H. Wilen, “Enantiomers, Racemates and Resolutions,” John WileyAnd Sons, Inc., 1981.

EXAMPLES

The present invention is further exemplified, but not limited, by thefollowing representative examples, which are intended to illustrate theinvention and are not to be construed as being limitations thereon. Thestructure of final products described herein can be confirmed bystandard analytical methods, e.g., spectrometric and spectroscopicmethods (e.g. MS, NMR). Abbreviations used are those conventional in theart. Compounds are purified by standard methods, e.g. crystallization,flash chromatography or reversed phase HPLC.

The following abbreviations will be used throughout the examples:

LIST OF ABBREVIATIONS

BINAP (+)-(1,1′-binaphthalene-2-2′diyl)bis(diphenylphosphine) DASTDiethylaminosulfur trifluoride Deoxofluor Bis(2-methoxyethyl)aminosulfurtrifluoride DCM Dichloromethane Di-^(t)bu 2-(Di-tert. Butylphosphino)2′,4′,6′-triisopropyl-1,1′- X-Phos biphenyl DIEA Diethylamine DIPEADiisoproylethylamine DMF Dimethylformamide HPLC High pressure liquidchromatography HR MS High resolution mass spectrometry HATU1-[Bis(dimethylamino)-methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium-3-oxide hexafluorophosphate HBTUO-Benzotriazol-1-yl-N,N,N′,N′-tetramethyluronium hexafluorophosphateHOBt 1-Hydroxy-1H-benzotriazol HMDS Hexamethyldisilazane MS Massspectrometry NBS N-Brom succinimide NMM N-methylmorpholine NMON-Methylmorpholine-N-oxide NMP N-methylpyrrolidine NMR Nuclear magneticresonance n.a. Not available n.d. Not determined RT, rt Room temperatureSEM 2-(Trimethylsilyl)ethoxymethyl TFA Trifluoroacetic acid THFTetrahydrofuran X-Phos2-(Dicyclohexylphosphino)-2′,4′,6′-triisopropyl-1,1′-biphenylCompound SynthesisPyridazine-Arylethers and -Anilines

As illustrated in Scheme 1, compounds of Formula Ia can be prepared fromintermediates IIIa (preparation described in Scheme 6), which can eitherreact with a phenol or aniline by direct thermal nucleophilicdisplacement or palladium-catalyzed nucleophilic displacement. CompoundsIa can be converted into further examples by functional groupmanipulations of R″.

Synthesis of Examples 1-5 Example 1(R)-4-(4,5-Dimethyl-6-phenoxy-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicmethyl ester

To a solution of(R)-4-(6-Chloro-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (compound 54, 40 mg, 0.106 mmol) in 2 mL toluene isadded phenol (45 mg, 0.48 mmol), potassium phosphate (40.6 mg, 0.19mmol) and di-^(t)bu X-Phos (5.3 mg, 0.014 mmol) in a 2 drum screw-topvial. The vial is evacuated and flushed with nitrogen, followed with theadditon of palladium (II) acetate (2 mg, 0.01 mmol). The reactionmixture is flushed with nitrogen again and heated to 100° C. for 16 h.The mixture is filtered through Celite and the filtrate is concentratedto afford a brown oil. The crude product is purified by HPLC, elutingwith 15-95% acetonitrile in water (both mobile phases modified with 3%n-PrOH) to provide the desired product as a white solid (9 mg, 22%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.69 (s, 1H), 8.39 (s, 1H), 7.40 (t, J=7.5Hz, 2H) 7.19 (t, J=7.5 Hz, 1H), 7.10 (d, J=7.5 Hz, 2H), 4.84-4.82 (m,1H), 4.42-4.38 (m, 1H), 3.81 (s, 3H), 3.45-3.25 (m, 3H), 3.02-2.99 (m,1H), 2.93-2.86 (m, 1H), 2.35 (s, 3H), 2.26 (s, 3H), 1.36 (d, J=6.6 Hz,3H).

HR MS (m/z, MH+) meas. 435.2157, calc. 435.2145.

Example 22-[(R)-4-(4,5-Dimethyl-6-phenoxy-pyridazin-3-yl)-2-methyl-3,4,5,6-tetra-hydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol

To a solution of(R)-4-(4,5-dimethyl-6-phenoxy-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicmethyl ester (98 mg, 0.226 mmol) in 2 mL anhydrous THF is added 3 Mmethylmagensium bromide (600 μL, 1.8 mmol) in a 2 drum septum-top vialat −78° C. under nitrogen atmosphere. The reaction mixture is stirred at−78° C. for 1.5 h, before being warmed to 0° C. and stirred foradditional 2 h. The reaction mixture is quenched with sat. aq. NH₄Cl at−78° C. and diluted with DCM. The organic solution is washed with brine,dried over Na₂SO₄ and concentrated to afford the crude material. Theresulting solid is purified by prep. HPLC, eluting with 10%-100%acetonitrile in water (both mobile phases modified by 3% n-PrOH).Fractions containing the desired product are combined and freeze-driedto afford a white solid (58 mg, 59%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.33 (s, 1H), 8.19 (s, 1H), 7.41 (t, J=7.6Hz, 2H) 7.20 (t, J=7.6 Hz, 1H), 7.11 (d, J=7.6 Hz, 2H), 5.09 (s, 1H),4.64 (m, 1H), 4.16-4.13 (m, 1H), 3.44-3.41 (m, 2H), 3.02-2.99 (m, 1H),2.89-2.85 (m, 1H), 2.34 (s, 3H), 2.25 (s, 3H), 1.41 (s, 6H), 1.28 (d,J=6.6 Hz, 3H).

HR MS (m/z, MH+) meas. 435.2508, calc. 435.2508.

Example 3(R)-4-(4,5-Dimethyl-6-phenylamino-pyridazin-3-yl)-2-methyl-3,4,5,6-tetra-hydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester

and

Example 4(R)-4-(4,5-Dimethyl-6-phenylamino-pyridazin-3-yl)-2-methyl-3,4,5,6-tetra-hydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid penylamide

To(R)-4-(6-chloro-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (compound 54, 250 mg, 0.663 mmol) is added aniline(2.4 mL, 26.5 mmol) in a microwave tube. The reaction mixture is heatedat 190° C. for 30 min in a microwave reactor. The reaction mixture isloaded on silica gel and purified by flash chromatography, eluting with50%-100% EtOAc:heptane for six column volumes, followed with 3%-10% MeOHin DCM. Both example 3 and 4 are collected and concentrated to affordwhite solids.

Example 3 130 mg, 45%

¹H NMR (400 MHz, CDCl₃) δ=8.83 (s, 1H), 8.16 (s, 1H), 7.41-7.32 (m, 4H),7.14-7.10 (m, 1H), 4.79-4.77 (m, 1H), 4.39-4.35 (m, 1H), 3.96 (s, 3H)3.52-3.45 (m, 2H), 3.35-3.42 (m, 1H), 3.24-3.21 (m, 1H), 3.12-3.07 (m,1H), 2.38 (s, 3H), 2.15 (s, 3H), 1.44 (d, J=6.7 Hz, 3H).

MS (m/z, MH+) meas. 434.4, calc. 434.2.

Example 4 30 mg, 9%

MS (m/z, MH+) meas. 495.6, calc. 495.2.

Example 52-[(R)-4-(4,5-Dimethyl-6-phenylamino-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol

To a solution of(R)-4-(4,5-dimethyl-6-phenylamino-pyridazin-3-yl)-2-methyl-3,4,5,6-tetra-hydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (example 3, 360 mg, 0.14 mmol) in 2 mL anhydrous THFis added 3 M methylmagnesium bromide (554 μL, 1.7 mmol) in a 2 drumseptum-top vial at −78° C. under nitrogen atmosphere. The reactionmixture is stirred at −78° C. for 1.5 h, before warmed to 0° C. andstirred for an additional 1 h. The reaction mixture is quenched withsat. aq. NH₄Cl at −78° C. and diluted with DCM. The organic solution iswashed with brine, dried over Na₂SO₄ and concentrated to afford thecrude material. The resulting solid is purified by prep. HPLC, elutingwith 10%-100% acetonitrile in water (both mobile phases modified by 3%n-PrOH). Fractions containing the desired product are combined andfreeze-dried to afford a white solid (25 mg, 42N.

¹H NMR (400 MHz, CDCl₃) δ=8.25 (s, 1H), 8.04 (s, 1H), 7.49 (d, J=7.5 Hz,2H), 7.31 (t, J=7.5 Hz, 2H), 7.02 (t, J=7.5 Hz, 1H), 6.59 (b, 1H),4.63-4.61 (m, 1H), 4.16-4.12 (m, 1H), 3.44-3.09 (m, 5H), 2.36 (s, 3H),2.18 (s, 3H), 1.56 (s, 6H), 1.39 (d, J=7.1 Hz, 3H).

HR MS (m/z, MH+) meas. 434.2667, calc. 434.2668.

Aryl-pyridazines

As illustrated in Scheme 2, compounds of Formula Ib can be prepared forexample by chloride displacement from a 1,4-dichloropyridazine II with apiperazine to yield intermediates III, which react with a boronic acidor ester in a Suzuki coupling to yield compounds IV. Nucleophilicaromatic substitution with e.g. arylchlorides under basic conditionsyields examples Ib (Route A). Alternatively, intermediates II can reactwith substituted amines to compounds IIIa which are substrates forSuzuki coupling reactions with boronic acids or esters to yield examplesIb (Route B, X=N, CH). Compounds Ib can be converted into furtherexamples by functional group manipulations of R″ e.g. by esterhydrolysis and amid formation or Grignard addition to esterfunctionalities.

Synthesis of Intermediates3-(4-Fluoro-phenyl)-4,5-dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazine(Compound 1)

To a round bottom flask is added3-chloro-4,5-dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazine (500mg, 2.07 mmol), 4-fluorophenylboronic acid (580 mg, 4.15 mmol) sodiumcarbonate (440 mg, 4.15 mmol), toluene (16 mL) and water (8 mL). Thereaction mixture is purged with nitrogen for 20 min.Tetrakis(triphenylphosphine) palladium (50 mg, 0.103 mmol) is added andthe mixture is heated to 110° C. for 18 h. The reaction mixture isconcentrated and partitioned between ethylacetate and water. It isextracted with ethylacetate twice and the combined organic phases aredried with sodium sulfate and concentrated. It is purified by columnchromatography (0-25% methanol/methylene chloride) to give 480 mg of3-(4-fluoro-phenyl)-4,5-dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazine(83%).

¹H NMR (400 MHz, CDCl₃) δ=7.34-7.49 (m, 2H) 7.07 (t, J=8.8 Hz, 2H) 3.35(m, 2H) 2.84-3.13 (m, 4H) 2.63 (dd, J=12.0 Hz, 10.0 Hz, 1H) 2.20 (s, 3H)2.14 (s, 3 H) 1.67 (br s, 1H) 1.05 (d, J=6.5 Hz, 3H).

HR MS (m/z, MH+) meas. 301.1824, calc. 301.1829.

3-(4-Trifluoromethyl-phenyl)-4,5-dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazine(Compound 2)

Compound 2 is prepared analogous to compound 1.

¹H NMR (400 MHz, CDCl₃) δ=7.69-7.80 (m, 2H) 7.60-7.70 (m, 2H) 3.38-3.52(m, 3 H) 2.98-3.22 (m, 4H) 2.69-2.83 (m, 1H) 2.30 (s, 3H) 2.23 (s, 3H)1.15 (d, J=6.4 Hz, 3H).

HR MS (m/z, MH+) meas. 351.1806, calc. 351.1797.

3-Chloro-4,5-dimethyl-6-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazine(Compound 3)

1-(5-Trifluoromethyl-pyridin-2-yl)-piperazine (10 g, 43.3 mmol) iscombined with 3,6-dichloro-4,5-dimethyl-pyridazine (14.4 g, 84.3 mmol),triethylamine (8.25 mL), and NMP (40 mL). The reaction mixture is heatedto a temperature of 180° C. for 25 min, and then concentrated in vacuo.The residue is purified by flash chromatography on silica gel (0-8%MeOH/CH₂Cl₂) to afford the title compound (13.2 g, 82%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.48-8.41 (m, 1H) 7.84 (dd, J=9.1 Hz, 2.4Hz, 1H) 7.03 (d, J=9.1 Hz, 1H) 3.88-3.76 (m, 4H) 3.28-3.20 (m, 4H) 2.31(s, 6H).

2-[4-(6-chloro-4,5-dimethyl-pyridazin-3-yl)-piperazin-1-yl]-4-trifluoromethyl-pyrimidine-5-carboxylicacid methyl ester (Compound 4)

To a roundbottom flask is added3-chloro-4,5-dimethyl-6-piperazin-1-yl-pyridazine (1 g, 4.41 mmol),2-chloro-4-trifluoromethyl-pyrimidine-5-carboxylic acid methyl ester(2.12 g, 8.82 mmol) and diisopropylethylamine (2.3 mL, 13.23 mmol) in adioxane (9 mL) solution and stirred for 18 h at room temperature. Filterthe reaction mixture and rinse with water and ethylacetate to give 1.35g of2-[4-(6-chloro-4,5-dimethyl-pyridazin-3-yl)-piperazin-1-yl]-4-trifluoromethyl-pyrimidine-5-carboxylicacid methyl ester (71%).

¹H NMR (400 MHz, CDCl₃) δ=8.96 (s, 1H), 4.09-4.22 (m, 4H), 3.93 (s, 3H),3.35 (m, 4H), 2.39 (s, 3H), 2.35 (s, 3H).

HR MS (m/z, MH+) meas. 431.1206, calc. 431.1210.

Synthesis of examples 6-9 via Route A Example 6(R)-4-[6-(4-fluoro-phenyl)-4,5-dimethyl-pyridazin-3-yl]-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester

Combine3-(4-fluoro-phenyl)-4,5-dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazine(522 mg, 1.73 mmol), 5-chloro-pyrazine-2-carboxylic acid methyl ester(360 mg, 2.07 mmol), diisopropylethylamine (900 μl, 5.19 mmol) anddioxane (3 mL) in a round bottom flask. Heat to 110° C. for 18 h.Concentrate reaction mixture and purify by column chromatography (0-100%ethylacetate/heptane gradient). Triturate product with acetonitrile togive 480 mg of(R)-4-[6-(4-fluoro-phenyl)-4,5-dimethyl-pyridazin-3-yl]-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (63%).

¹H NMR (400 MHz, CDCl₃) δ=8.87 (s, 1H) 8.21 (s, 1H) 7.46-7.60 (m, 2H)7.19 (t, J=8.5 Hz, 2H) 4.84 (br s, 1H) 4.43 (d, J=13.0 Hz, 1H) 3.99 (s,3H) 3.68 (d, J=12.5 Hz, 1H) 3.49-3.63 (m, 2H) 3.39 (dd, J=12.8 Hz, 3.8Hz, 1H) 3.15-3.31 (m, 1H) 2.41 (s, 3H) 2.29 (s, 3H) 1.50 (d, J=6.5 Hz,3H).

HR MS (m/z, MH+) meas. 437.2097, calc. 437.2101.

Example 7(R)-4-[6-(4-trifluoromethyl-phenyl)-4,5-dimethyl-pyridazin-3-yl]-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester

Example 7 is prepared in a analogous fashion to example 6 from compound2.

¹H NMR (400 MHz, CDCl₃) δ=8.87 (s, 1H), 8.21 (d, J=1.3 Hz, 1H),7.72-7.82 (m, 2H), 7.68 (d, J=8.1 Hz, 2H), 4.85 (br s, 1H), 4.44 (d,J=13.3 Hz, 1 H), 4.00 (s, 3H), 3.70 (d, J=14.1 Hz, 1H), 3.50-3.64 (m,2H), 3.41 (dd, J=12.6 Hz, 3.6 Hz, 1H), 3.18-3.31 (m, 1H), 2.42 (s, 3H),2.29 (s, 3H), 1.50 (d, J=6.7 Hz, 3H).

HR MS (m/z, MH+) meas. 487.2050, calc. 487.2069.

Example 8(R)-4-[6-(4-trifluoromethyl-phenyl)-4,5-dimethyl-pyridazin-3-yl]-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid

To a solution of example 7 (0.26 g, 0.53 mmol) and methanol (10 mL) isadded 50% aqueous LiOH aqueous (10 mL). The mixture is stirred at roomtemperature overnight. Solvent is removed. The residue is dissolved inwater and acidified with 3N HCl to pH about 7 and extracted with ethylacetate. The ethyl acetate layer is concentrated to afford the titlecompound (0.25 g, 98%) as a yellow solid.

¹H NMR (400 MHz, CD₂Cl₂) δ=8.90 (s, 1H), 8.12 (s, 1H), 7.81 (d, J=8.0Hz, 2H), 7.69 (d, J=8.0 Hz, 2H), 4.88 (m, 1H), 4.48 (d, J=13.0 Hz, 1H),3.66 (m, 3H), 3.40 (m, 1H), 3.23 (m, 1H), 2.43 (s, 3H), 2.27 (s, 3H),1.53 (d, J=6.5 Hz, 3H).

HR MS (m/z, MH+) meas. 473.1900.

Example 9(R)-4-[6-(4-fluoro-phenyl)-4,5-dimethyl-pyridazin-3-yl]-2-methyl-3,4,5,6-tetrahydro-2H-[1,2]bipyrazinyl-5′-carboxylicacid

To a solution of example 6 (0.74 g, 1.31 mmol) and methanol (10 mL) isadded sodium hydroxide (100 mg). The mixture is stirred at roomtemperature overnight. Solvent is removed and the residue is dissolvedin water and acidified with 3 N HCl to pH about 7, and extracted withethyl acetate. The ethyl acetate layer is concentrated to afford thetitle compound (0.68 g, 96%) as a yellow solid.

¹H NMR (400 MHz, CD₂Cl₂) δ=8.90 (s, 1H), 8.11 (s, 1H), 7.52 (m, 2H),7.22 (m, 2H), 4.67 (m, 1H), 4.48 (d, J=12.0 Hz, 1H), 3.65 (m, 3H), 3.40(m, 1H), 3.26 (m, 1H), 2.46 (s, 3H), 2.32 (s, 3H), 1.53 (d, J=6.5 Hz,3H).

HR MS (m/z, MH+) meas. 423.1941.

Synthesis of Examples 10-40 via Route B

General Protocol for the Suzuki Coupling of Boronic Acids to PyridazinylChlorides IIIa

Method A

In a round bottom flask, combine 3-chloro-pyridazine (0.268 mmol),boronic acid (0.537 mmol) and sodium carbonate (57 mg, 0.537 mmol) in 1mL of water and 1.8 mL of THF. Purge reaction mixture with nitrogen for20 min, then add tetrakis(triphenylphosphine) palladium (10 mg) and heatto 110° C. for 18 h. Purify by column chromatography on silica gel witha 0%-70% ethylacetate/heptane gradient. Triturate products with methanoland acetonitrile to remove other impurity the desired products.

Method B

In a round bottom flask combine 3-chloro-pyridazine (0.268 mmol),boronic acid (0.536 mmol) and cesium carbonate (175 mg, 0.536 mmol) in 2mL of 1,4-dioxane. Purge reaction mixture with nitrogen for 1 min andadd tetrakis(triphenylphosphine) palladium (30 mg, 0.026 mmol). Heat to115° C. for 18 h. Filter reaction mixture through Celite andconcentrate. Partition between ethyl acetate and water, collect organiclayer. Extract again with ethyl acetate and combine organics. Dry withsodium sulfate, filter and concentrate. Triturate material withacetonitrile, followed by a recrystallization from hot acetonitrile togive the desired products.

Method C

In a microwave vial, combine 3-chloro-pyridazine (0.080 mmol), boronicacid (0.096 mmol), potassium phosphate (34 mg, 0.161 mmol) and X-Phos(1.3 mg) in a n-butanol solution (1.5 mL). Purge with nitrogen for 1minute and add palladium acetate (1 mg) then heat in a microwave reactorfor 45 min at 150° C. Filter and concentrate reaction mixture, followedby purification on preparative HPLC (water/acetonitrile with 1% ammoniumhydroxide) to yield the desired products.

Method D

In a microwave vial, 3-chloro-pyridazine (0.268 mmol), boronic acid(0.322 mmol), potassium phosphate (110 mg, 0.537 mmol) and X-Phos (5 mg)in a n-butanol solution (2.5 mL). Purge with nitrogen for 1 min and addpalladium acetate (3.5 mg,) then heat in a microwave reactor for 45 minat 150° C. Filter and concentrate reaction mixture. Partition betweenethylacetate and water, collecting the organic layer. Extract again andcombine organics, dry with sodium sulfate and concentrate. Purify bycolumn chromatography in a 0-100% ethylacetate/heptane gradient to yieldthe desired products.

Examples 10-31

The following table (Table 1) lists examples of compounds prepared byRoute B using the general methods A-D described above:

TABLE 1 Example Structure HR MS[m/z, MH+] meas. 10

A 482.1757 (calc. 482.1779) 11

A 414.1904 (calc. 414.1906) 12

A 432.1807 (calc. 432.1811) 13

B 444.2008 (calc. 444.2011) 14

B 456.2366 (calc. 456.2375) 15

B 448.1513 (calc. 448.1516) 16

C 415.1859 (calc. 415.1858) 17

D 457.1746 (calc. 457.1764) 18

B 507.1503 (calc. 507.1523) 19

B 503.1996 (calc. 503.2018) 20

B 525.1407 (calc. 525.1429) 21

D 530.2487 (calc. 530.2487) 22

D 530.2482 (calc. 530.2491) 23

D 548.2383 (calc. 548.2397) 24

D 546.2433 (calc. 546.2440) 25

D 558.2236 (calc. 558.2241) 26

D 557.2830 (calc. 557.2852) 27

B 471.1700 (calc. 471.1712) 28

B 449.2304 (calc. 449.2304) 29

B 471.1721 (calc. 471.1712) 30

B 495.2520 (calc. 495.2508) 31

D 420.2498 (calc. 420.2512)

Synthesis of Examples 32-34 Via Grignard Addition to Esters

General Protocol for the Grignard Addition

To a round bottom flask, cooled to −78° C., containing a solution ofester (1 mmol) in anhydrous THF (4 mL) is added a 3M solution ofmethylmagnesiumbromide (8 mmol) in diethyl ether, dropwise. Allow towarm up to 0° C. and after 20 minutes of stirring quench with asaturated solution of aqueous ammonium chloride. Extract withethylacetate twice and collect organics. Dry with sodium sulfate andconcentrate. Purify by column chromatography in a 0-100%ethylacetate/heptane gradient. Triturate product with acetonitrile andfilter to give 2-propan-ol.

Examples 32-34

The following table (Table 2) lists examples of compounds prepared bythe general procedure described above:

TABLE 2 Example Structure HR MS [m/z, MH+] meas. 32

437.2453 (calc. 437.2465) 33

487.2430 (calc. 487.2433) 34

503.2406 (calc. 503.2382)

Synthesis of Examples 35-40 Via Amide Formation

General Protocol for the Amide Formation

The mixture of example 8 (40.0 mg, 0.08 mmol), HATU (64.0 mg, 0.17mmol), diisopropylethyl amine (44.0 mg, 0.34 mmol), dimethylacetamide(1.5 mL) and amine (0.13 mmol) is stirred at room temperature for 10 h.The crude product is purified by HPLC (C18 column, acetonitrile/water(3% propanol), 30%˜100%) to afford the examples 35 to 40 (74%˜82%).

Examples 35-40

The following table (Table 3) lists examples of compounds prepared bythe general procedure described above:

TABLE 3 Example Structure HR MS [m/z, MH+] meas. 35

604.2988 36

542.2468 37

598.2762 38

590.2831 39

583.2758 40

619.2410Piperidin-4-yl-pyridazines

As illustrated in Scheme 3, compounds of Formula Ic can be prepared bySuzuki coupling of protected 1,2,3,6-tetrahydro-pyridine-4-boronic acidswith pyridazine chlorides V to yield intermediates VI which afterprotecting group removal and nucleophilic displacement provideintermediates VII. Hydrogenation furnishes examples Ic.

Synthesis of Intermediates4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-3,6-dihydro-2H-pyridine-1-carboxylicacid tert-butyl ester (Compound 5)

To a solution of 3-benzyl-6-chloro-4,5-dimethylpyridazine (800 mg, 3.44mmol) in 20 mL DMF is added tert-butyl4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-5,6-dihydropyridine-1(2H)-carboxylate(1.3 g, 4.1 mmol), followed with potassium carbonate (1.43 g, 10.3 mmol)and Pd(PPh₃)₄ (397 mg, 0.344 mmol) in a round bottom flask. The vial isevacuated and flushed with nitrogen. The reaction mixture is heated to100° C. for 16 h. The mixture is filtered through Celite and thefiltrate is concentrated to afford the crude material. The mixture ispurified by flash chromatography on silica gel, eluting with 3%-15%MeOH:DCM. Fractions containing the desired product are combined andconcentrated to afford a brown solid (1.0 g, 77%).

¹H NMR (400 MHz, CD₂Cl₂) δ=7.30-7.21 (m, 5H), 5.84-5.82 (s, 1H), 4.43(s, 2H), 4.13-4.11 (m, 2H), 3.69 (t, J=5.5 Hz, 1H), 2.56-2.54 (m, 2H),2.26 (s, 3H), 2.20 (s, 3H), 1.49 (s, 9H).

MS (m/z, MH+) meas. 380.7, calc. 380.23.

Methyl5-(4-(6-benzyl-4,5-dimethylpyridazin-3-yl)-5,6-dihydropyridin-1(2H)-yl)pyrazine-2-carboxylate(Compound 6)

To4-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-3,6-dihydro-2H-pyridine-1-carboxylicacid tert-butyl ester (170 mg, 0.358 mmol) is added 50% TFA in DCM. Thereaction mixture is stirred for 10 min and concentrated to afford3-benzyl-4,5-dimethyl-6-(1,2,3,6-tetrahydropyridin-4-yl)pyridazine as ayellow sticky solid (125 mg, 100%). To a solution of3-benzyl-4,5-dimethyl-6-(1,2,3,6-tetrahydropyridin-4-yl)pyridazine (180mg, 0.644 mmol) in dioxane is addedmethyl-5-chloropyrazine-2-carboxylate (222 mg, 1.29 mmol) and TEA (0.45mL, 3.22 mmol) in a microwave tube. The reaction mixture is heated at160° C. for 40 min in a microwave reactor. The mixture is concentratedto afford a brown oil and purified by prep HPLC, eluting with 10%-100%acetonitrile:water (both mobile phases modified by 3% n-PrOH). Fractionscontaining the desired product are combined and freeze-dried to afford awhite solid (80 mg, 30%).

MS (m/z, MH+) meas. 416.5, calc. 416.2.

3-Benzyl-4,5-dimethyl-6-(1-(5-(trifluoromethyl)pyridin-2-yl)-1,2,3,6-tetrahydropyridin-4-yl)pyridazine(Compound 7)

To a solution of3-benzyl-4,5-dimethyl-6-(1,2,3,6-tetrahydropyridin-4-yl)pyridazine (70mg, 0.175 mmol) in 2 mL dioxane is added2-chloro-5-(trifluoromethyl)pyridine (64 mg, 0.35 mmol) and TEA (0.122mL, 0.88 mmol) in a microwave tube. The reaction mixture is heated at160° C. for 40 min in a microwave reactor. The mixture is concentratedto afford a brown oil and purified by prep HPLC, eluting with 10%-100%acetonitrile:water (both mobile phases modified by 3% n-PrOH). Fractionscontaining the desired product are combined and freeze-dried to afford awhite solid (33 mg, 42%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.44 (s, 1H), 7.83 (dd, J=2.5 Hz, 9.1 Hz,2H), 7.30-7.26 (m, 2H), 7.20-7.16 (m, 3H), 6.99-6.97 (d, J=9.1 Hz, 1H),5.96-5.94 (m, 1H), 4.32 (s, 2H), 4.27-4.26 (m, 2H), 3.97 (t, J=5.6 Hz,2H), 2.60-2.58 (m, 2H), 2.22 (s, 3H), 2.16 (s, 3H).

HR MS (m/z, MH+) meas. 425.1958, calc. 425.1953.

Synthesis of Examples 41-44 Example 41 Methyl5-(4-(6-benzyl-4,5-dimethylpyridazin-3-yl)piperidin-1-yl)pyrazine-2-carboxylate

To a solution of methyl5-(4-(6-benzyl-4,5-dimethylpyridazin-3-yl)-5,6-dihydropyridin-1(2H)-yl)pyrazine-2-carboxylate(60 mg, 0.144 mmol) in 20 mL EtOH is added 10% Pd—C (77 mg, 72 mmol).The reaction mixture is stirred under hydrogen atmosphere for 16 h. Themixture is filtered through Celite and the filtrate is concentrated toafford a yellow solid (60 mg, 100%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.66 (s, 1H), 8.43 (s, 1H), 7.28-7.26 (m,2H), 7.19-7.15 (m, 3H), 4.67-4.64 (m, 2H), 4.27 (s, 2), 3.81 (s, 3H),3.43-3.39 (m, 1H), 3.26-3.17 (m, 2H), 2.27 (s, 3H), 2.14 (s, 3H),1.92-1.86 (m, 4H).

HR MS (m/z, MH+) meas. 418.2247, calc. 418.2243.

Example 422-{5-[4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidin-1-yl]-pyrazin-2-yl}-propan-2-ol

and

Example 433-Benzyl-6-{1-[5-(1-methoxy-1-methyl-ethyl)-pyrazin-2-yl]-piperidin-4-yl}-4,5-dimethyl-pyridazine

To a solution of methyl5-(4-(6-benzyl-4,5-dimethylpyridazin-3-yl)piperidin-1-yl)pyrazine-2-carboxylate(30 mg, 0.07 mmol) in 2 mL anhydrous THF is added 3 M CH₃MgBr (287 μL,0.862 mmol) at −78° C. under nitrogen atmosphere. The reaction mixtureis stirred at −78° C. for 1 h and stirred at 0° C. for an additional 1h. The mixture is quenched with sat. aq. ammonium chloride at −78° C.and the mixture is partitioned between DCM and brine. The organic layeris dried over Na₂SO₄ and concentrated to afford a brown oil. The mixtureis purified by prep HPLC, eluting with 10%-100% acetonitrile:water (bothmobile phases modified by 3% n-PrOH). Both examples 42 and 43 arecollected as white solid.

-   Example 42 (8 mg, 27%): ¹H NMR (400 MHz, DMSO-d₆) δ=8.33 (s, 1H),    8.26 (s, 1H), 7.28-7.24 (m, 2H), 7.19-7.15 (m, 3H), 5.08 (s, 3H),    5.08 (s, 1H), 4.45-4.41 (m, 2H), 4.27 (s, 2H), 3.34-3.24 (m, 2H),    2.27 (s, 3H), 2.15 (s, 3H), 1.92-1.83 (m, 4 H), 1.42 (s, 6H).

HR MS (m/z, MH+) meas. 418.2625, calc. 418.2607.

-   Example 43 (6 mg, 20%): ¹H NMR (400 MHz, DMSO-d₆) δ=8.30 (s, 1H),    8.20 (s, 1H), 7.28-7.25 (m, 2H), 7.19-7.15 (m, 3H), 4.49-4.45 (m,    2H), 4.27 (s, 2H), 3.34-3.26 (m, 1H), 3.09-3.03 (m, 2H), 3.05 (s,    3H), 2.27 (s, 3H), 2.14 (s, 3H), 1.91-1.84 (m, 4 H), 1.45 (s, 6H).

HR MS (m/z, 2M+H⁺) meas. 863.5453, calc. 863.5448.

Example 443-Benzyl-6-{1-[5-(trifluoromethyl)pyridin-2-yl]-piperidin-4-yl}-4,5-dimethyl-pyridazine

To a solution of3-benzyl-4,5-dimethyl-6-(1-(5-(trifluoromethyl)pyridin-2-yl)-1,2,3,6-tetrahydropyridin-4-yl)pyridazine(20 mg, 0.047 mmol) in 8 mL EtOH is added 10% Pd—C (25 mg, 19 mmol). Thereaction mixture is stirred under hydrogen atmosphere for 16 h. Themixture is filtered through Celite and the filtrate is concentrated toafford a off-white solid. The mixture is purified by prep HPLC, elutingwith 10%-100% acetonitrile:water (both mobile phases modified by 3%n-PrOH). Fractions containing the desired product are combined andfreeze-dried to afford a white solid (8 mg, 40%).

MS (m/z, MH+) meas. 427.4, calc. 427.48.

Arylacyl-, Arylhydroxymethyl- and Arylmethyl-Pyridazines

As illustrated in Scheme 4, dichloro-pyridazines II can be reacted witharyl-substituted acetonitrile after deprotonation and subsequentoxidation (e.g with air) to arylacyl compounds VIII. Nucleophilicdisplacement of the chlorine with amines provides examples Id which canbe further reduced with e.g. NaBH₄ to examples Ie (Route A) Reaction ofintermediates VIII with piperazines provides compounds IX which afterWolf-Kishner reduction yield intermediates X which after a nucleophilicdisplacement reaction furnish examples If (Route B). Further functionalgroup transformations at R″ can provide additional examples. Examples Idand Ie can also be transformed into examples with a —CF₂— and —CHF—linker between Ar and the pyridazine moiety by oxygen-fluor exchange.

Synthesis of Intermediates(R)-2-Methyl-4-boc-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (Compound 8)

To (R)-1-boc-methylpiperazine (1 g, 5.0 mmol) in DMF (20 mL) is added5-chloro-pyrazine-2-carboxylic acid methyl ester (862 mg, 5.0 mmol) andNa₂CO₃ (2.1 g, 20.0 mmol). The reaction mixture is stirred in amicrowave reactor at 140° C. for 3 h. Then the mixture is cooled to rtand the organic solvent is removed in vacuo to afford a brown coloredsolid as product (1.7 g, quant.).

MS (m/z, MH+) meas. 337.

(R)-2-Methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylic acidmethyl ester (Compound 9)

To a solution of(R)-2-methyl-4-boc-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (2 g, 5.94 mmol) in MeOH (17 mL) is added HCl (4M indioxane, 4.5 mL, 18 mmol). The reaction mixture is stirred at 70° C. for1 h. The reaction solution is concentrated, dissolved in DCM and organiclayer is washed with Na₂CO₃ to adjust the pH value to 8.0. The solventsare removed under reduced pressure to afford a brown oil (1.2 g, 77%).

1H NMR (400 MHz, DMSO-d₆) δ=8.81 (s, 1H), 8.11 (s, 1H), 4.58 (m, 1H),4.22 (d, J=13.1 Hz, 1H), 3.96 (s, 3H), 3.21 (m, 2H), 3.17 (m, 1H), 3.07(m, 1H), 2.18 (m, 1H), 1.35 (d, J=6.5 Hz, 3H).

MS (m/z, MH+) meas. 237.

2-((R)-2-Methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl)-propan-2-ol(Compound 10)

To a solution of(R)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylic acidmethyl ester (60 mg, 0.24 mmol) in THF (3 mL) at −78° C. is added MeMgBr(3 M solution in Et₂O 640 μl, 1.9 mmol). The reaction mixture is stirredat 0° C. for 2 h. The reaction mixture is quenched with sat. aqueousNH₄Cl (3 mL). Additional water is added and the mixture is extractedwith EtOAc; the organic layer is washed with NaHCO₃. Purification byHPLC of the crude product with acetonitrile in water (from 5% to 80%with 3% 1-propanol) at 220 nm wavelength detection provides the desiredproduct as yellow colored oil (20 mg, 35%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.30 (s, 1H), 8.10 (s, 1H), 5.06 (s, 1H),4.40 (m, 1H), 3.91 (m, 1H), 3.98 (m, 2H), 2.85 (m, 2H), 2.65 (m, 1H),1.40 (s, 6H), 1.13 (d, J=6.6 Hz, 3H).

MS (m/z, MH+) meas. 237.

(6-Chloro-4,5-dimethyl-pyridazin-3-yl)-phenyl-methanone (Compound 11)

3,6-Dichloro-4,5-dimethyl-pyridazine (1.00 g, 5.65 mmol) and phenylacetonitrile (652 mL, 5.65 mmol) are dissolved in toluene (17.5 mL),cooled to 0° C. and charged with NaHMDS (5.65 mL, 2M in THF, 11.3 mmol).The reaction mixture is stirred for 16 h, slowly warming up from 0° C.to rt. The mixture is stirred vigorously at the open air for another 24h. The mixture is quenched by the addition of aqueous NaHCO₃ solution,the layers are separated and the aqueous phase is extracted with DCM.The combined organic phases are concentrated to give the title compoundas a brown solid (1.4 g, quant.).

¹H NMR (400 MHz, CDCl₃) δ=7.82 (m, 2H), 7.55 (m, 1H), 7.40 (m, 2H), 2.39(s, 3H), 2.28 (s, 3H).

MS (m/z, MH+) meas. 247.4.

(6-Chloro-4,5-dimethyl-pyridazin-3-yl)-pyridin-4-yl-methanone (Compound12)

According to the protocol described below,3,6-dichloro-4,5-dimethyl-pyridazine (1.00 g, 5.65 mmol) and4-pyridylacetonitrile hydrochloride (1.05 g, 6.79 mmol) afforded thetitle compound as a white solid (822 mg, 59%).

(6-Chloro-4,5-dimethyl-pyridazin-3-yl)-pyridin-3-yl-methanone (Compound13)

3,6-Dichloro-4,5-dimethyl-pyridazine (1.00 g, 5.65 mmol) is added to anoven-dried, 250-mL round-bottom flask under N₂ followed by THF (50 mL)and pyridin-3-yl-acetonitrile (800 mg, 7.68 mmol). The reaction isdegassed with a flow of N₂ for 30 min. NaHMDS (14.13 mL, 1.0 M, 14.13mmol) is added and the reaction is stirred for 16 h. The reactionmixture is then transferred to a beaker and stirred vigorously underopen to the atmosphere for several hours. The reaction is quenched withsaturated sodium bicarbonate solution, and the organics are extractedwith dichloromethane. The combined organic layers are washed with brine,dried over Na₂SO₄, filtered and concentrated under reduced pressure. Thecrude material is purified via flash chromatography on silica gel (0-20%methanol in CH₂Cl₂) to afford the title compound (1.3 g, 93%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.97 (s, 1H), 8.80 (d, J=4.5 Hz, 1H), 8.25(d, J=8.0 Hz, 1H), 7.60-7.64 (m, 1H), 2.44 (s, 3H), 2.33 (s, 3H).

(6-Chloro-4,5-dimethyl-pyridazin-3-yl)-pyridin-2-yl-methanone (Compound14)

3,6-Dichloro-4,5-dimethyl-pyridazine (1.00 g, 5.65 mmol) is added to adry 250-ml round-bottom flask under N₂ followed by THF (50 mL) andpyridin-2-yl-acetonitrile (800 mg, 7.68 mmol). The reaction is degassedfor 30 min. NaHMDS (1.0 M, 14.13 mL, 14.13 mmol) is added and thereaction is stirred overnight. The reaction mixture is transferred to abeaker and air stirred vigorously for several hours. The reactionmixture is quenched with saturated sodium bicarbonate solution. Theorganics are extracted with dichloromethane. The combined organic layersare washed with brine and dried over Na₂SO₄, filtered and concentratedunder reduced pressure. The crude material is purified via flashchromatography on silica gel (0-20% methanol in CH₂Cl₂) to afford thetitle compound (616 mg, 44%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.68 (m, 1H), 8.26 (m, 1H), 8.16 (m, 1H),7.76 (m, 1H), 2.45 (s, 3H), 2.21 (s, 3H).

[4,5-Dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazin-3-yl]-pyridin-4-yl-methanone(Compound 15)

According to the protocol described below,(6-chloro-4,5-dimethyl-pyridazin-3-yl)-pyridin-4-yl-methanone (750 mg,3.03 mmol) and (R)-2-methyl-piperazine (364 mg, 3.63 mmol) afforded thetitle compound as a beige solid (778 mg, 83%).

[4,5-Dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazin-3-yl]-pyridin-3-yl-methanone(Compound 16)

(6-Chloro-4,5-dimethyl-pyridazin-3-yl)-pyridin-3-yl-methanone (1.2 g,4.84 mmol) and (R)-2-methyl-piperazine (485 mg, 4.84 mmol) are added toa microwave vial followed by NMP (17 mL) and triethylamine (2.01 mL,14.49 mmol). The vial is sealed and irradiated in the microwave at 170°C. for 30 min. The crude material is directly purified via flashchromatography on silica gel (0-20% methanol in CH₂Cl₂). The resultingoil is co-evaporated with CH₂Cl₂ and heptane to afford the titlecompound as a powder (1350 mg, 90%).

¹H NMR (400 MHz, DMSO-d₆) δ=9.56 (br s, 1H), 8.96 (s, 1H), 8.84-8.86 (m,1H), 8.21-8.24 (m, 1H), 7.60-7.63 (m, 1H), 3.72 (s, 1H), 3.69 (s, 1H),3.45-3.50 (m, 1H), 3.26-3.31 (m, 4H), 2.30 (s, 6H), 1.32 (d, J=6.5 Hz,3H).

[4,5-Dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazin-3-yl]-pyridin-2-yl-methanone(Compound 17)

(6-Chloro-4,5-dimethyl-pyridazin-3-yl)-pyridin-2-yl-methanone (550 mg,2.22 mmol), (R)-2-methyl-piperazine (320 mg, 3.20 mmol) are added into amicrowave vial followed by NMP (6 mL) and triethylamine (0.92 mL, 6.66mmol). The vial is sealed and irradiated in the microwave at 180° C. for1 h. The crude material is directly purified via flash chromatography onsilica gel (20-70% methanol in CH₂Cl₂) to afford the title compound (671mg, 97%).

¹H NMR (400 MHz, DMSO-d₆) δ=9.57 (br s, 1H), 8.66 (d, J=5.0 Hz, 1H),8.10-8.17 (m, 2H), 7.69-7.73 (m, 1H), 3.65 (m, 1H), 3.62 (m, 1H),3.45-3.50 (m, 1H), 3.12-3.33 (m, 4H), 2.29 (s, 3H), 2.15 (s, 3H), 1.32(d, J=6.5 Hz, 3H).

4,5-Dimethyl-3-((R)-3-methyl-piperazin-1-yl)-6-pyridin-4-ylmethyl-pyridazine(Compound 18)

According to the protocol described below,4,5-dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazin-3-yl]-pyridin-4-yl-methanone(550 mg, 1.77 mmol), hydrazine monohydrate (0.43 mL, 8.84 mmol), and KOHpellets (495 mg, 8.82 mmol) afforded the title compound (372 mg, 71%).

4,5-Dimethyl-3-((R)-3-methyl-piperazin-1-yl)-6-pyridin-3-ylmethyl-pyridazine(Compound 19)

4,5-Dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazin-3-yl]-pyridin-3-yl-methanone(1300 mg, 4.17 mmol), hydrazine monohydrate (1045 mg, 20.88 mmol), KOHpellets (1171.4 mg, 20.88 mmol), and diethylene glycol (26 mL) are addedto a round-bottom flask and the reaction is heated at 190° C. for 4 h.The reaction mixture is allowed to warm to room temperature and pouredinto water. The organics are extracted with dichloromethane. Thecombined organic layers are washed with brine, dried over Na₂SO₄,filtered and concentrated under reduced pressure. The crude material ispurified via flash chromatography on silica gel (50/40/10CH₂Cl₂/MeOH/NH₄OH)) to afford the title compound (1.17 g, 94%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.47 (s, 1H), 8.41-8.42 (m, 1H), 7.54-7.56(m, 1H), 7.29-7.32 (m, 1H), 4.25 (s, 2H), 4.12 (br s, 1H), 3.17-3.22 (m,3H), 2.72-2.94 (m, 4H), 2.17 (s, 3H), 2.13 (s, 3H), 0.99 (d, J=6.0 Hz,3H).

Synthesis of Examples 45-55 Example 45(R)-4-(6-Benzoyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester

To (R)-2-methyl-3,4,56-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (100 mg, 0.403 mmol) in DMF (5 mL) is added(6-chloro-4,5-dimethyl-pyridazin-3-yl)-phenyl-methanone (100 mg, 0.402mmol) and sodium carbonate (170.7 mg, 1.61 mmol) and the reactionmixture is heated in a microwave reactor for 4 h at 180° C. Then thereaction mixture is diluted with DCM (25 mL) and washed with NaHCO₃ andwater. Organic solvent is extracted and removed under reduced pressure.The crude product is purified by HPLC with acetonitrile in water (from20% to 100% with 3% 1-propanol) at 220 nm wavelength detection tocollect the desired product as an off white powder (58 mg, 32%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.65 (s, 1H), 8.35 (s, 1H), 7.48-7.65 (m,5H), 4.39 (d, J=13.1 Hz, 1H), 3.54 (d, J=12.6 Hz, 1H), 3.29 (m, 2H),3.17 (m, 3H), 2.31 (s, 3H), 2.18 (s, 3H), 1.30 (s, 3H).

HR MS (m/z, MH+) meas. 446.5098, calc. 446.5104.

Example 46(6-{(R)-4-[4-(1-Hydroxy-1-methyl-ethyl)-phenyl]-3-methyl-piperazin-1-yl}-4,5-dimethyl-pyridazin-3-yl)-phenyl-methanone

To (6-chloro-4,5-dimethyl-pyridazin-3-yl)-phenyl-methanone (50 mg, 0.20mmol) in DMF (3 mL) was added2-[4-(R)-2-methyl-piperazine-1-yl]-phenyl]propan-2-ol (47.4 mg, 0.20mmol) and sodium carbonate (86.2 mg, 0.81 mmol), the reaction mixturewas heated in a microwave reactor for 4 h at 180° C. Then the reactionmixture is diluted with DCM (15 mL) and washed with NaHCO₃ and water.Organic solvent is extracted and removed under reduced pressure.Purification by HPLC of the crude product with ACN in water (from 20% to100% with 3% 1-propanol) at 220 nm UV detection provides the desiredproduct as off white powder (25 mg, 28%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.42 (s, 1H), 8.23 (s, 1H), 7.61-7.89 (m,5H), 4.77 (m, 1H), 4.25 (d, J=12.6 Hz, 1H), 3.75 (d, J=12.6 Hz, 1H),3.65 (d, J=12.6 Hz, 1H), 3.29 (m, 2H), 3.11 (m, 1H), 2.50 (s, 3H), 2.32(s, 3H), 1.47 (s, 6H), 1.35 (d, J=6.6 Hz, 3H).

HR MS (m/z, MH+) meas. 444.2256, calc. 444.2651.

Example 47(R)-4[6-(hydroxyl-phenyl-methyl)-4,5-dimethyl-pyridazin-3-yl]-2-methyl-3,4,5,6-tetrahydro-2H-[1,2]bipyrazinyl-5′-carboxylicacid methyl ester

To (R)-4-(6-benzoyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylic acid methyl ester (8 mg,0.017 mmol) in MeOH (2 mL) is added sodium borohydride (170 μg, 0.004mmol) in 15 minutes and the reaction mixture is stirred at roomtemperature for 1 h. The reaction mixture is diluted with DCM and washedwith NaHCO₃ and water. The organic solvent is separated and the solventis removed under reduced pressure. Purification by HPLC of the crudeproduct with acetonitril in water (from 10% to 100% with 3% 1-propanol)at 220 nm wavelength detection provides the desired product as off whitepowder. (6 mg, 79%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.77 (s, 1H), 8.47 (s, 1H), 7.29-7.38 (m,5H), 6.15 (s, 1H), 4.92 (m, 1H), 4.50 (m, 1H), 3.89 (s, 3H), 3.49-3.61(m, 3H), 3.17-3.02 (m, 2H), 2.30 (s, 3H), 2.14 (s, 3H), 1.43 (d, J=6.6Hz, 3H).

MS (m/z, MH+) meas. 449.

Example 482-{(R)-4-[6-(Hyrdoxyl-phenyl-methyl0-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2]bipyrazinyl-5′-yl]-propan-2-ol

To(R)-4[6-(hydroxyl-phenyl-methyl)-4,5-dimethyl-pyridazin-3-yl]-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (15 mg, 0.032 mmol) in THF (2 mL) is added methylmagnesium bromide (32 μl, 0.095 mmol) at −78° C. and the reactionmixture is stirred 0° C. for 2 h. The reaction mixture is diluted withDCM and washed with NH₄Cl and water. The organic solvent is separatedextracted and concentrated under reduced pressure. Purification by HPLCof the crude product with acetonitrile in water (from 10% to 100% with3% 1-propanol) at 220 nm wavelength detection provides the desiredproduct as off white powder (11 mg, 77%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.27 (s, 1H), 8.07 (s, 1H), 7.29-7.34 (m,5H), 5.88 (s, 1H), 4.67 (m, 1H), 4.19 (m, 1H), 3.61 (m, 1H), 3.52-3.31(m, 3H), 3.19 (tt, J=3.5 Hz, 12.7 Hz, 1H), 2.29 (s, 3H), 2.05 (s, 3H),1.57 (s, 6H), 1.40 (d, J=6.6 Hz, 3H).

HR MS (m/z, MH+) meas. 449.2649, calc. 444.2665.

Example 49(R)-4-(4,5-Dimethyl-6-pyridin-4-ylmethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester

According to the protocol described below for example 46,4,5-dimethyl-3-((R)-3-methyl-piperazin-1-yl)-6-pyridin-4-ylmethyl-pyridazine(155 mg, 0.51 mmol) and 5-chloro-pyrazine-2-carboxylic acid methyl ester(99 mg, 0.56 mmol) afforded the title compound as an orange oil (123 mg,56%).

Example 502-[(R)-4-(4,5-Dimethyl-6-pyridin-4-ylmethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol

According to the protocol described below,(R)-4-(4,5-dimethyl-6-pyridin-4-ylmethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (110 mg, 0.25 mmol) and MeMgI (0.660 mL, 1.98 mmol)afforded the title compound as a yellow powder (40 mg, 37%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.47 (d, J=5.5 Hz, 2H), 8.36 (s, 1H), 8.21(s, 1H), 7.21 (d, J=5.5 Hz, 2H), 5.15 (s, 1H), 4.68 (br s, 1H), 4.29 (s,2H), 4.17 (d, J=12.5 Hz, 1H), 3.21-3.59 (m, 3H), 3.07 (dd, J=12.5 Hz,3.5 Hz, 1H), 2.89-3.00 (m, 1H), 2.28 (s, 3H), 2.13 (s, 3H), 1.42 (s,6H), 1.28 (d, J=6.5 Hz, 3H).

HR MS (m/z, MH+) meas. 434.2650, calc. 434.2668.

Example 51(R)-4-(4,5-Dimethyl-6-pyridin-3-ylmethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester

4,5-Dimethyl-3-((R)-3-methyl-piperazin-1-yl)-6-pyridin-3-ylmethyl-pyridazine(350 mg, 1.18 mmol) and 5-chloro-pyrazine-2-carboxylic acid methyl ester(243.7 mg, 1.41 mmol) are added to a microwave vial followed by NMP (7mL) and triethylamine (0.49 mL, 3.54 mmol). The vial is sealed andirradiated in the microwave at 145° C. for 30 min. The crude material isdirectly purified via flash chromatography on silica gel (0-20% methanolin CH₂Cl₂) to afford the title compound (30 mg, 6%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.71 (s, 1H), 8.52 (d, J=6 Hz, 1H), 8.48 (s,1H), 8.42 (s, 1H), 7.57 (d, J=8 Hz, 1H), 7.30-7.33 (m, 1H), 4.85 (m,1H), 4.45 (d, J=12 Hz, 1H), 4.29 (s, 2H), 3.79 (s, 3H), 3.41-3.55 (m,3H), 3.08 (m, 1H), 2.93-2.99 (m, 1H), 2.28 (s, 3H), 2.17 (s, 3H), 1.36(d, J=7 Hz, 3H).

Example 522-[(R)-4-(4,5-Dimethyl-6-pyridin-3-ylmethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol

(R)-4-(4,5-Dimethyl-6-pyridin-3-ylmethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (25 mg, 0.058 mmol) is added to an oven-dried,round-bottom flask under N₂ followed by THF (0.6 mL). The reaction isthen placed in a dry-ice bath for 15 min. MeMgI (0.15 mL, 3.0 M, 0.461mmol) is added drop-wise and the reaction is stirred at −78° C. for 30min. The reaction is warmed to 0° C. and stirred 30 min or untilcomplete conversion is observed. The reaction mixture is quenched withsaturated ammonium chloride solution. The organics are extracted withethyl acetate. The combined organic layers are dried over Na₂SO₄,filtered and concentrated under reduced pressure. The crude material ispurified via flash chromatography on silica gel (2% CH₂Cl₂, 98%(50/30/20 ethyl acetate/heptane/MeOH)) to afford the title compound (3.5mg, 14%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.49 (s, 1H), 8.42 (d, J=6.7 Hz, 1H), 8.36(s, 1H), 8.21 (s, 1H), 7.57 (d, J=7.9 Hz, 1H), 7.32 (m, 1H), 5.13 (s,1H), 4.67 (s, br, 1H), 4.29 (s, 2H), 4.17 (d, J=12.5 Hz, 1H), 3.51 (d,J=12.5 Hz, 1H), 3.34-3.42 (m, 2 H), 3.07 (dd, J=12.1 Hz, 1H), 2.93-2.97(dt, J=3.4 Hz, 12.5 Hz, 1H), 2.28 (s, 3H), 2.17 (s, 3H), 1.43 (s, 6H),1.28 (d, J=6.5 Hz, 3H).

HR MS (m/z, MH+) meas. 434.2663, calc. 434.2668.

Example 53(R)-4-(4,5-Dimethyl-6-pyridin-2-ylmethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester

Step 1: Preparation of 2,4-dimethyl-3-pyridin-2-ylmethyl-pentan-3-ol(Compound 20)

2-Methyl-pyridine (1.86 g, 20 mmol) is dissolved in THF (20 mL) andcooled to −30° C. tert-Butyl lithium (11.8 mL, 1.7M in pentane, 20 mmol)is added dropwise to the solution, and the reaction is stirred for 30min at −30° C. 2,4-Dimethyl-pentan-3-one (3.4 mL, 24 mmol) is added andthe reaction is warmed to room temperature and stirred for 2 h. Add H₂O(30 mL) and extract with EtOAc. Wash combined organics with brine andconcentrate in vacuo. The residue is purified by flash chromatography onsilica gel (EtOAc/Heptane) to afford2,4-dimethyl-3-pyridin-2-ylmethyl-pentan-3-ol (4.14 g, quant.).

Step 2:(R)-4-(4,5-Dimethyl-6-pyridin-2-ylmethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (example 53)

(R)-4-(6-Chloro-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (250 mg, 0.663 mmol) is combined with2,4-dimethyl-3-pyridin-2-ylmethyl-pentan-3-ol (114.6 mg, 0.553 mmol),cesium carbonate (216.2 mg, 0.664 mmol), palladium triflate (6.2 mg,0.028 mmol), tricyclohexyl phosphine (15.5 mg, 0.055), and toluene (2mL). The reaction mixture is heated to 110° C. for 65 h to reach 10%conversion. Add H₂O and extract with EtOAc. Concentrate combinedorganics in vacuo. The residue is purified by flash chromatography onsilica gel (MeOH/CH₂Cl₂) to afford the title compound (13 mg, 5.4%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.71 (d, J=1.3 Hz, 1H), 8.46-8.43 (m, 1H),8.41 (d, J=1.3 Hz, 1H), 7.71 (td, J=7.7 Hz, 1.8 Hz, 1H), 7.27-7.18 (m,2H), 4.86 (br s, 1H), 4.41 (s, 2H), 4.48-4.38 (m, 1H), 3.83 (s, 3H),3.59-3.38 (m, 3H), 3.08 (dd, J=12.6 Hz, 3.7 Hz, 1H), 2.95 (td, J=12.2Hz, 3.2 Hz, 1H), 2.28 (s, 3H), 2.16 (s, 3H), 1.36 (d, J=6.6 Hz, 3 H).

HR MS (m/z, MH⁺) meas. 434.2236, calc. 434.2304.

Example 542-[(R)-4-(4,5-Dimethyl-6-pyridin-2-ylmethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol

Example 54 is prepared from example 53 by addition of MeMgI as describedfor example 52.

HR MS (m/z, MH+) meas. 434.2666, calc. 434.2668.

Example 552-{(R)-4-[6-(Difluoro-phenyl-methyl)-4,5-dimethyl-pyridazin-3-yl]-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl}-propan-2-ol

Step 1:3-Chloro-4,5-dimethyl-6-(2-phenyl-[1,3]dithiolan-2-yl)-pyridazine(Compound 21)

To a DCM solution of(6-chloro-4,5-dimethyl-pyridazin-3-yl)-phenyl-methanone (300 mg, 1.22mmol) is added 1,2-ethandithiol (0.408 ml, 4.86 mmol) and BF₃.OEt₂(0.154 ml, 1.216 mmol) at 0° C. under nitrogen atmosphere. The reactionmixture is stirred at room temperature for 16 h. The reaction wascharged with BF₃.OEt₂ (0.154 ml, 1.216 mmol) and 1,2-ethandithiol (0.408ml, 4.86 mmol), and heated at 40° C. for 6 h. The reaction is quenchedwith sat. NaHCO₃ at 0° C. and organic phase is washed with brine. Theorganic layer is dried over Na₂SO₄, filtered and concentrated to afforda yellow solid. The residue is loaded on silica gel and purified byflash chromatography, eluting with 20-80% EtOAc: heptane. Fractionscontaining the desired product are combined and concentrated to afford awhite solid (280 mg, 73%).

¹H NMR (400 MHz, CDCl₃) δ=7.54-7.53 (m, 2H), 7.28-7.22 (m, 3H),3.46-3.34 (m, 4H), 2.30 (s, 3H), 1.94 (s, 3H).

MS (m/z, MH+) meas. 323.0, calc. 322.88.

Step 2: 3-Chloro-6-(difluoro-phenyl-methyl)-4,5-dimethyl-pyridazine(Compound 22)

To a DCM (1 mL) solution of NBS (49.6 mg, 0.279 mmol) is added DAST(0.147 ml, 1.115 mmol). The reaction mixture is cooled to 0° C. before3-chloro-4,5-dimethyl-6-(2-phenyl-[1,3]dithiolan-2-yl)-pyridazine (90mg, 0.279 mmol) is added. The mixture is stirred at room temperature for3 h Additional 2 eq. of DAST (73.7 μL, 0.558 mmol) are added and themixture stirred for another 2 h. The reaction mixture is quenched withsat. NaHCO₃ at 0° C. The aqueous layer is washed with DCM and thecombined organic layers are dried over Na₂SO₄ and concentrated to affordthe crude mixture. The residue is loaded on silica gel and purified byflash chromatography, eluting with 15-45% EtOAc:heptane. Fractionscontaining the desired product are combined and concentrated to afford ayellow oil (15 mg, 20%).

¹H NMR (400 MHz, CDCl₃) δ=7.54-7.52 (m, 2H), 7.47-7.43 (m, 3H),2.42-2.41 (m, 6H).

¹⁹F NMR (400 MHz, CDCl₃) δ=−89.9.

MS (m/z, MH+) meas. 269.2, calc. 269.06

Step 3:2-{(R)-4-[6-(Difluoro-phenyl-methyl)-4,5-dimethyl-pyridazin-3-yl]-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl}-propan-2-ol(Example 55)

Example 55 is prepared from compounds 10 and 22 as described for example46.

Piperidin-1-yl-Pyridazines

As illustrated in Scheme 5, piperidin-1-yl-pyridazines can be preparedby a multitude of routes. According to Route A functionalizedpiperidines can react with intermediates V to yield examples Ig.Examples Ih and Ii can be prepared via Route B. Reaction of V with a4-piperidinyl-carboxylic ester provides after ester hydrolysisintermediates XIa which can react either to imidazol-substitutedexamples Ih or can be condensed with ortho-dianilines to examples Ii.Route C provides examples Ij by reacting intermediates V with4-cyanopiperidine and subsequent Pd-catalyzed reaction of XIb withR″—Br. Further imidazol-substituted examples Ik can be prepared fromintermediates XIc (by condensation reaction in the presence of ammoniaand a keto-aldehyde precursor) which are available by reaction of4-hydroxymethyl-piperidines with V and subsequent oxidation of thealcohol functionality (Route D). Route E provides ketones XId which canact as electrophiles for metallo-organic reagents such as R″—Li toprovide tertiary alcohol examples Il. Transformation of the hydroxylgroup with fluorination reagants e.g. Deoxofluor yields further examplesIn. Ketones XId can be used in reductive amination reactions with aminesand e.g. NaBH(OAc)₃ as reducing agent to yield examples Io.

Synthesis of Example 56 by Route A Example 562-[1-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidin-4-yl]-2,3dihydro-1H-isoindole

Step 1:8-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-1,4-dioxa-8-aza-spiro[4.5]decane(Compounds 23)

Compound 23 is prepared from 3-benzyl-6-chloro-4,5-dimethylpyridazineand 1,4-dioxa-8-aza-spiro[4.5]decane following the procedure similar towhat described for compound 3.

¹H-NMR (400 MHz, CDCl₃) δ=1.89 (4H, m), 2.08 (3H, s), 2.17 (3H, s), 3.33(4H, m), 4.00 (4H, s), 4.29 (2H, s), 7.22 (5H, m).

MS (m/z, MH+) meas. 340.4.

Step 2: 1-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidin-4-one(Compound 24)

To compound 23 (917 mg, 2.46 mmol) in acetone (50 mL) is addedhydrochloric acid (1.2 N, 20 mL). The mixture is stirred for 46 h, thentreated with saturated sodium bicarbonate to slightly basic, andextracted with ethyl acetate (3×). The organic extracts are washed withbrine, dried to give an oil that provides pure 24 as thick oil (565 mg,78%) after purification by silica gel chromatography (40% ethyl acetatein heptane).

¹H-NMR (400 MHz, CDCl₃) δ=2.1 (3H, s), 2.2 (3H, s), 2.7 (4H, m), 3.6(4H, m), 4.3 (2H, s), 7.3 (5H, m).

HR MS (m/z, MH+) meas. 296.1763.

Step 3:2-[1-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidin-4-yl]-2,3dihydro-1H-isoindole(Example 56)

To ketone 24 (43 mg, 0.15 mmol) in anhydrous THF/CH₂Cl₂ (1.5 ml/1.5 mL)is added isoindoline (25 μL, 0.22 mmol) and glacial acidic acid (3 μL)and triacetoxyl sodium borohydride (98 mg, 0.44 mmol). The mixture isstirred for 2 h and, quenched with saturated sodium bicarbonate, andextracted with CH₂Cl₂. The organic phase is dried, rotavaped, and wassubjected to HPLC purification (aetonitrile-water-0.1% TFA) to give thetitle compound as a TFA salt (67 mg, 89%).

¹H-NMR (400 MHz, CDCl₃) δ=2.2 (4H, m), 2.3 (3H, s), 2.4 (3H, s), 3.2(2H, m), 3.6 (1H, m), 3.8 (2H, m), 4.5 (4H, bs), 5.1 (2H, bs), 7.3 (9H,m).

HR MS (m/z, MH+) meas. 399.2547.

Synthesis of Examples 57-59 by Route B Example 573-Benzyl-6-[4-(5-chloro-1H-imidazol-2-yl)-piperidin-1-yl]-4,5-dimethyl-pyridazine

Step 1: 1-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidine-4-carboxylicacid ethyl ester (Compound 25)

To a solution of 3-benzyl-6-chloro-4,5-dimethyl-pyridazine (1.0 g, 4.31mmol) in NMP (10 mL) is added piperidine-4-carboxylic acid ethyl ester(2.0 g, 12.9 mmol) and DIPEA (3.7 mL, 21.6 mmol). The mixture is heatedin microwave at 210° C. for 1.5 h. The mixture is concentrated at 80° C.by rotovaporation. The crude product is purified by HPLC (CH₃CN/H₂O:22%˜45% with 0.1% TFA) to give1-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidine-4-carboxylic acidethyl ester (0.94 g, 61%).

¹H-NMR (400 MHz, CDCl₃) δ=1.28 (3H, t), 1.90 (2H, q), 2.07 (2H, d), 2.23(3H, s), 2.33 (3H, s), 2.54 (1H, m), 3.03 (2H, t), 3.57 (2H, d), 4.17(2H, q), 4.50 (2H, s), 7.19 (2H, d), 7.24 (1H, d), 7.29 (2H, t).

HR MS (m/z, MH+) meas. 354.2179.

Step 2: 1-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidine-4-carboxylicacid (Compound 26)

To a solution of1-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidine-4-carboxylic acidethyl ester (0.88 g, 2.5 mmol) in EtOH (8 mL) is added a solution ofsodium hydroxide (0.8 g, 20.1 mmol) in H₂O (8 mL). After being stirredat 25° C. for 2 h, the mixture is concentrated, and extracted withCH₂Cl₂ (2×10 mL) to remove impurities. The aqueous layer is acidified by1N HCl to pH ˜5, and extracted with CH₂Cl₂ (6×20 mL). The combinedorganic solution is dried over Na₂SO₄, filtered and concentrated to give1-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidine-4-carboxylic acid(0.68 g, 83%).

¹H-NMR (400 MHz, CDCl₃) δ=1.92 (2H, q), 2.08 (2H, d), 2.25 (3H, s), 2.35(3H, s), 2.64 (1H, m), 3.11 (2H, t), 3.60 (2H, d), 4.49 (2H, s), 7.20(2H, d), 7.26 (1H, t), 7.31 (2H, t).

HR MS (m/z, MH+) meas. 326.1870.

Step 3: 1-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidine-4-carboxylicacid cyanomethyl-amide (Compound 27)

To a solution of1-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidine-4-carboxylic acid(350 mg, 1.08 mmol) in DMF (10 mL) is added DIPEA (0.94 mL, 5.4 mmol)and HATU (490 mg, 1.29 mmol). After being stirred at 25° C.,aminoacetonitrile hydrochloride (119 mg, 1.29 mmol) is added. Themixture is stirred for 2 h, and diluted with EtOAc (20 mL) and washedwith H₂O (3×10 mL). The organic layer is dried over Na₂SO₄, filtered andconcentrated. The crude product is purified by chromatography(CH₂Cl₂/MeOH: 97%/3%) to give1-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidine-4-carboxylic acidcyanomethyl-amide (280 mg, 72%).

¹H-NMR (400 MHz, CDCl₃) δ=1.97 (4H, m), 2.25 (3H, s), 2.36 (3H, s), 2.58(1H, m), 3.07 (2H, t), 3.67 (2H, d), 4.12 (2H, d), 4.44 (2H, s), 7.14(2H, d), 7.31 (3H, m).

MS (m/z, MH+) meas. 364.3.

Step 4:3-Benzyl-6-[4-(5-chloro-1H-imidazol-2-yl)-piperidin-1-yl]-4,5-dimethyl-pyridazine(Example 57)

To a solution of1-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidine-4-carboxylic acidcyanomethyl-amide (20 mg, 0.055 mmol) and triphenyl phosphine inacetonitrile (1 mL) at 25° C. is added carbon tetrachloride (42 mg, 0.28mmol). After being stirred at 50° C. for 3 h, the mixture isconcentrated, and diluted with CH₂Cl₂ (10 mL) and washed with sodiumhydroxide (2 mL, 1N), and H₂O (2 mL), dried over Na₂SO₄, filtered andconcentrated. The crude product is purified by HPLC (CH₃CN/H₂O: 22%˜45%with 0.1% TFA) to give3-benzyl-6-[4-(5-chloro-1H-imidazol-2-yl)-piperidin-1-yl]-4,5-dimethyl-pyridazine(11.8 mg, 56%).

¹H-NMR (400 MHz, MeOH-d₄) δ=2.09 (2H, m), 2.20 (2H, d), 2.35 (3H, s),2.50 (3H, s), 3.20 (3H, m), 3.87 (2H, d), 4.46 (2H, s), 7.25 (2H, d),7.34 (1H, t), 7.35 (1H, s), 7.39 (2H, t).

HR MS (m/z, MH+) calc. 382.1794.

Example 582-[1-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidin-4-yl]-1H-imidazo[4,5-b]pyridine

To a solution of1-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidine-4-carboxylic acid(compound 26, 50 mg, 0.15 mmol) and 2,3-diaminopyridine (33 mg, 0.30mmol) in CH₂Cl₂ (0.5 mL) is added polyphosphoric acid (1 mL). Themixture is concentrated to remove CH₂Cl₂. After being stirred at 150° C.for 1.5 h, the mixture is cooled to 25° C., diluted with water (10 mL),and basified by 10% aqueous solution of sodium hydroxide to pH ˜8. Theaqueous solution is extracted with CH₂Cl₂ (5×15 mL). The combinedorganic layers are concentrated and purified by HPLC (CH₃CN/H₂O: 22%˜45%with 0.1% TFA) to give2-[1-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidin-4-yl]-1H-imidazo[4,5-b]pyridine(33.8 mg, 55%).

¹H-NMR (400 MHz, MeOH-d₄) δ=2.28 (2H, qd), 2.36 (3H, s), 2.38 (2H, dd),2.53 (3H, s), 3.29 (2H, t), 3.56 (1H, m), 3.93 (2H, d), 4.48 (2H, s),7.25 (2H, d), 7.32 (1H, t), 7.39 (2H, t), 7.70 (1H, dd), 8.46 (1H, d),8.62 (1H, d).

HR MS (m/z, MH+) meas. 399.2294.

Example 592-[1-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-4-methyl-piperidin-4-yl]-1H-imidazo[4,5-c]pyridine

Step 1:1-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-4-methyl-piperidine-4-carboxylicacid ethyl ester (Compound 28)

To a solution of 3-benzyl-6-chloro-4,5-dimethyl-pyridazine (1.0 g, 4.3mmol) in NMP (10 mL) is added 4-methyl-piperidine-4-carboxylic acidethyl ester (2.0 g, 8.6 mmol) and DIPEA (3.7 mL, 21.6 mmol). The mixtureis heated in microwave at 210° C. for 1.5 h. The mixture is concentratedat 80° C. by rotovaporation. The crude product is purified by HPLC(CH₃CN/H₂O: 22%˜45% with 0.1% TFA) to give1-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-4-methyl-piperidine-4-carboxylicacid ethyl ester (0.64 g, 41%).

¹H-NMR (400 MHz, CDCl₃) δ=1.27 (3H, s), 1.29 (3H, t), 1.62 (2H, t), 2.24(3H, s), 2.27 (2H, d), 2.34 (3H, s), 3.13 (2H, t), 3.47 (2H, d), 4.20(2H, q), 4.42 (2H, s), 7.11 (2H, d), 7.28 (3H, m).

HR MS (m/z, MH+) meas. 368.2335.

Step 2:1-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-4-methyl-piperidine-4-carboxylicacid (Compound 29)

To a solution of1-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-4-methyl-piperidine-4-carboxylicacid ethyl ester (0.60 g, 1.6 mmol) in EtOH (5 mL) is added sodiumhydroxide (0.5 g, 13.2 mmol) in H₂O (5 mL). After being stirred at 25°C. for two hr, the mixture is concentrated, and extracted with CH₂Cl₂(2×10 mL) to remove impurities. The aqueous layer is acidified by 1N HClto pH ˜5, and extracted with CH₂Cl₂ (6×20 mL). The combined organicsolution is dried over Na₂SO₄, filtered and concentrated to give1-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-4-methyl-piperidine-4-carboxylicacid (0.49 g, 89%).

¹H-NMR (400 MHz, CDCl₃) δ=1.33 (3H, s), 1.60 (2H, t), 2.13 (3H, s), 2.23(3H, s), 2.31 (2H, d), 3.17 (2H, t), 3.38 (2H, d), 4.42 (2H, s), 7.21(2H, d), 7.27 (3H, t).

HR MS (m/z, MH+) meas. 340.2028.

Step 3:2-[1-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-4-methyl-piperidin-4-yl]-1H-imidazo[4,5-c]pyridine(Example 59)

To a solution of1-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-4-methyl-piperidine-4-carboxylicacid (50 mg, 0.15 mmol) and 2,3-diaminopyridine (32 mg, 0.29 mmol) inCH₂Cl₂ (0.5 mL) is added polyphosphoric acid (1 mL). The mixture isconcentrated to remove CH₂Cl₂. After being stirred at 150° C. for 3.5 h,the mixture is cooled to 25° C., diluted with water (3 mL), and basifiedby 10% aqueous solution of sodium hydroxide to pH ˜8. The aqueous isextracted with CH₂Cl₂ (3×10 mL). The combined organic layers areconcentrated and purified by HPLC (CH₃CN/H₂O: 15%˜40% with 0.1% TFA) togive2-[1-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-4-methyl-piperidin-4-yl]-1H-imidazo[4,5-c]pyridine(21 mg, 27%).

¹H-NMR (400 MHz, MeOH-d₄) δ=1.60 (3H, s), 2.15 (2H, t), 2.34 (3H, s),2.49 (3H, s), 2.65 (2H, d), 3.35 (2H, d), 3.65 (2H, d), 4.43 (2H, s),7.22 (2H, d), 7.31 (1H, t), 7.37 (2H, t), 8.12 (1H, d), 8.56 (1H, d),9.23 (1H, s).

HR MS (m/z, MH+) meas. 413.2446.

Synthesis of Example 60 by Route C Example 601′-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-5-(1-hydroxy-1-methyl-ethyl)-2′,3′,5′,6′-tetrahydro-1′H-[2,4]bipyridinyl-4′-carbonitrile

Step 1:1-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidine-4-carbonitrile(Compound 30)

Compound 30 is prepared from compound 10 and piperidine-4-carbonitrilefollowing the procedure similar to what described for compound 3.

¹H-NMR (400 MHz, CDCl₃) δ=2.0-2.2 (4H, m), 2.1 (3H, s), 2.2 (3H, s), 2.8(1H, m), 3.1 (2H, m), 3.4 (2H, m), 4.3 (2H, s), 7.2 (5H, m).

HR MS (m/z, MH+) meas. 307.1930.

Step 2: 2-(6-Bromo-pyridin-3-yl)-propan-2-ol (Compound 31)

To 2-bromo-5-iodo-pyridine (2.974 g, 10.2 mmol) in a mixture of THF (15mL) and ether (20 mL) at −78° C. is added dropwise n-butyl lithium (2.5M in hexane, 4 L, 10.2 mmol). The mixture is stirred at −78° C. for 30min, then acetone (anhydrous, 0.749 uL, 10.2 mmol) is added drop wise.The mixture is slowly warmed up to −50° C. over 1.5 h and is quenchedwith saturated ammonium chloride, extracted with ethyl acetate. Theorganic phase is separated, dried and rotavaped. The residue is purifiedby silica gel chromatography (10-20% ethyl acetate in heptane) to givethe title compound as white solid (1.40 g, 64%).

¹H-NMR (400 MHz, CDCl₃) δ=1.60 (6H, s), 1.96 (1H, s), 7.45 (1H, d, J=8Hz), 7.70 (1H, dd, J=4, 8 Hz), 8.47 (1H, s).

HR MS (m/z, MH+) meas. 216.0034.

Step 3:1′-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-5-(1-hydroxy-1-methyl-ethyl)-2′,3′,5′,6′-tetrahydro-1′H-[2,4′]bipyridinyl-4′-carbonitrile(Example 60)

To a mixture of compound 30 (122 mg, 0.398 mmol) and compound 31 (103mg, 0.478 mmol) in anhydrous toluene (3 mL) is added Pd₂(dba)₃ (18 mg,0.020 mmol). The mixture is bubbled with nitrogen for 7 min, to which isadded tri-t-butylphosphine (1.0 M in toluene, 40 μL, 0.040 mmol) andlithium hexamethyldisilazide (1.0 M in toluene, 0.995 uL. 0.995 mmol).The mixture is stirred at rt for 15 min, then at 60° C. for 3 h, andcooled to rt. Additional Pd₂(dba)₃ (18 mg), tri-t-butylphosphine (40 μL)and lithium hexamethyldisilazide (0.995 μL) are added to the reactionmixture. After being stirred for 17 h, the mixture is quenched withsaturated ammonium chloride and extracted with ethyl acetate. Theorganic phase was washed with brine and dried, rotavaped and purifiedthrough preparative HPLC (acetonitrile-water-0.1% THF) to give the titlecompound as a TFA salt (24 mg, 11%).

¹H-NMR (400 MHz, CDCl₃) δ=1.63 (6H, s), 2.23 (2H, m), 2.27 (3H, s), 2.41(3H, s), 2.58 (2H, m), 3.57 (2H, m), 3.81 (2H, m), 4.52 (2H, s), 7.30(5H, m), 7.68 (1H, d, J=12 Hz), 7.96 (1H, m), 8.79 (1H, s).

HR MS (m/z, MH+) meas. 442.2600.

Synthesis of Example 61 by Route D Synthesis of Intermediates(5′-Benzyl-3′,4′-dimethyl-3,4,5,6-tetrahydro-2H-[1,2]bipyridinyl-4-yl)-methanol(Compound 32)

To the solution of piperidin-4-yl-methanol (125 mg, 1.03 mmol) in NMP (3mL) is added 3-benzyl-6-chloro-4,5-dimethyl-pyridazine (60 mg, 0.258mmol) and TEA. The reaction mixture is stirred at 210° C. in a microwavereactor for 2 h. Then the reaction mixture is diluted with DCM (15 mL)and washed with NaHCO₃ and water. The organic solvent is separated andremoved under reduced pressure. Purification by HPLC of the crudeproduct with acetonitrile in water (from 20% to 100% with 3% 1-propanol)at 220 nm wavelength detection provides the desired product as off whitepowder (200 mg, 62%).

¹H NMR (400 MHz, DMSO-d₆) δ=7.23-7.36 (m, 5H), 4.55 (t, J=5.3 Hz, 1H),4.29 (s, 2H), 3.45 (m, 2H), 2.85 (m, 2H), 2.57 (s, 1H), 2.21 (s, 3H),2.14 (s, 3H), 1.84 (m, 2H), 1.62 (m, 1H), 1.40 (m, 2H).

HR MS (m/z, MH+) meas. 312.2069, calc. 312.2076.

1-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidine-4-carbaldehyde(Compound 33)

To5′-benzyl-3′,4′-dimethyl-3,4,5,6-tetrahydro-2H-[1,2]bipyridinyl-4-yl)-methanol(155 mg, 0.473 mmol) in DCM (5 mL) is added Dess-Martin reagent (257 mg,0.59 mmol), the reaction mixture is stirred at room temperature for 2 h.Then the reaction mixture is diluted with DCM and washed with NaHCO₃ andwater. The organic phase is separated and the solvent removed underreduced pressure. Purification by HPLC of the crude product withacetonitrile in water (from 20% to 95% with 3% 1-propanol) at 220 nmwavelength detection provides the desired product as off white powder(120 mg, 78%).

MS (m/z, MH+) meas. 310.

Example 613-Benzyl-4,5-dimethyl-6-[4-(4-trifluoromethyl-1H-imidazol-2-yl)-piperidin-1-yl]-pyridazine

To the solution of sodium acetate trihydrate (50 mg, 0.615 mmol) inwater (5 mL) is added 1,1-dibromo-3,3,3-trifluoroacetone (83.5 mg, 0.307mmol). The solution is heated 45 min at 100° C. bath temperature andthen cooled. The solution is added to a solution of1-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidine-4-carbaldehyde (100mg, 0.31 mmol) in MeOH (5 mL) and concentrated aqueous ammonia in MeOH(1.7 mL, 7M, 12 mmol). The reaction mixture is allowed to stand for 3.5h at room temperature and the reaction mixture is then concentratedunder reduced pressure to yield a semi-solid which is recrystallizedfrom heptane to yield crude product. Purification by HPLC of the crudeproduct with acetonitrile in water (from 10% to 100% with 3% 1-propanol)at 220 nm wavelength detection provides the desired product as off whitepowder (28 mg, 22%).

¹H NMR (400 MHz, DMSO-d₆) δ=7.72 (s, 1H), 7.23-7.36 (m, 5H), 4.29 (s,2H), 3.52 (m, 1H), 3.37 (m, 2H), 2.97 (m, 2H), 2.24 (s, 3H), 2.20-1.97(m, 4H), 2.14 (s, 3H).

HR MS (m/z, MH+) meas. 416.2050, calc. 416.2062.

Synthesis of Examples 62-64 by Route E Example 622-[1-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-piperidin-4-yl]-1,2,3,4-tetrahydro-isoquinoline

This compound as a TFA salt is prepared from compound 24 and1,2,3,4-tetrahydro-isoquinoline following a procedure used in example56.

¹H-NMR (400 MHz, MeOH-d₄) δ=2.1 (2H, m), 2.3 (3H, s), 2.3 (2H, m), 2.4(3H, s), 3.1-3.9 (9H, m), 4.4 (2H, s), 4.6 (2H, s), 7.3 (9H, m).

HR MS (m/z, MH+) meas. 413.2689.

Example 631′-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-5-(1-hydroxy-1-methyl-ethyl)-2′,3′,5′,6′-tetrahydro-1′H-[2,4′]bipyridinyl-4′-ol

Step 1:2-Bromo-5-[1-methyl-1-(2-trimethylsilanyl-ethoxymethoxy)-ethyl]-pyridine(Compound 34) 84

To compound 31 (532 mg, 2.46 mmol) in anhydrous DMF (5 mL) at 0° C. isadded sodium hydride (60% in mineral oil, 138 mg, 3.45 mmol). Themixture is stirred at rt for 1 h and then cooled to 0° C., to which isadded SEMCl (0.564 uL, 3.2 mmol). The mixture is stirred at rt for 16 h,50° C. for 1 h, cooled to it and quenched with water, extracted withethyl acetate. The organic phase is washed with brine, dried androtavaped. The oily residue is purified by silica gel chromatography(10-15% ethyl acetate in heptane) to afford the title compound as clearoil (474 mg, 56%).

¹H-NMR (400 MHz, CDCl₃) δ=0.0 (9H, s), 0.84 (2H, m), 1.59 (6H, s), 3.60(2H, m), 4.60 (2H, s), 7.43 (1H, d, J=8 Hz), 7.61 (1H, m), 8.42 (1H, s).

HR MS (m/z, MH+) meas. 346.0822.

Step 2:1′-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-5-[1-methyl-1-(2-trimethylsilanyl-ethoxymethoxy)-ethyl]-2′,3′,5′,6′-tetrahydro-1′H-[2,4′]bipyridinyl-4′-ol(Compound 35)

To compound 34 (272 mg, 0.786 mmol) in THF (6 mL) at −78° C. is addedt-butyl lithium (1.7 M in pentane, 1.0 mL, 1.7 mmol). The mixture isstirred at −78° C. for 30 min, to which compound 24 (209 mg, 0.707 mmol)in THF (2 mL) is added at −78° C. The mixture is stirred and warmed upslowly to −40° C. in 1 h, then quenched at −40° C. with saturatedammonium chloride. THF is removed and the residue was extracted withethyl acetate (3×). The organic phase is washed with brine, dried overanhydrous Na₂SO₄ and concentrated. The residue is purified by silica gelchromatography (40-60% ethyl acetate in heptane) to provide recoveredcompound 24 (103 mg, 49%) and the title compound 35 (106 mg, 27%) as awhite solid.

¹H-NMR (400 MHz, CDCl₃) δ=0.0 (9H, s), 0.87 (2H, t, J=8 Hz), 1.64 (6H,s), 1.74 (2H, m), 2.10 (3H, s), 2.22 (3H, s), 2.28 (2H, m), 3.57 (6H,m), 4.31 (2H, s), 4.66 (2H, s), 4.95 (1H, s), 7.27 (5H, m), 7.43 (1H,m), 7.80 (1H, m), 8.62 (1H, m).

HR MS (m/z, MH+) meas. 563.3392.

Step 3:1′-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-5-(1-hydroxy-1-methyl-ethyl)-2′,3′,5′,6′-tetrahydro-1′H-[2,4]bipyridinyl-4′-ol(Example 63)

To compound 35 (44 mg, 0.078 mol) in CH₂Cl₂ (1.5 mL) at 0° C. is addedTFA (0.15 μL). The mixture is stirred at 0° C. for 2 h and is quenchedwith 25% ammonium acetate, extracted with ethyl acetate. The organicphase is washed with brine, dried and concentrated to give a yellowresidue which is purified by silica gel chromatography (0-5% methanol inCH₂Cl₂) to give the desired product (17 mg, 50N.

¹H-NMR (400 MHz, CDCl₃) δ=1.62 (6H, s), 1.72 (2H, m), 2.09 (3H, s), 2.21(3H, s), 2.25 (2H, m), 3.50 (4H, m), 4.30 (2H, s), 7.20 (5H, m), 7.42(1H, m), 7.86 (1H, m), 8.66 (1H, b.s).

HR MS (m/z, MH+) meas. 433.2590.

Example 642-[1′-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-4′-fluoro-1′,2′,3′,4′,5′,6′-hexahydro-[2,4′]bipyridinyl-5-yl]-propan-2-ol

Step 1:1′-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-4′-fluoro-5-[1-methyl-1-(2-trimethylsilanyl-ethoxymethoxy)-ethyl]-1′,2′,3′,4′,5′,6′-hexahydro-[2,4′]bipyridinyl(Compound 36)

To compound 35 (39 mg, 0.069 mmol) at 0° C. is added cold deoxofluor(50% in THF, 665 μL, 1.38 mmol). The mixture is stirred at rt for 4 h,washed with saturated NaHCO₃, extracted with CH₂Cl₂ (3×). The organicphase is washed with brine, dried and concentrated to afford brown oil.Silica gel chromatography purification affords the titled compound (21mg, 48%).

¹H-NMR (400 MHz, CDCl₃) δ=0.0 (9H, s), 0.9 (2H, t, J=8 Hz), 1.6 (6H, s),2.0 (2H, m), 2.1 (3H, s), 2.2 (3H, s), 2.6 (2H, m), 3.4 (4H, m), 3.6(2H, t, J=8 Hz), 4.3 (2H, s), 4.7 (2H, s), 7.2 (5H, m), 7.6 (1H, m), 7.8(1H, m), 8.6 (1H, b.s).

HR MS (m/z, MH+) meas. 565.3369.

Step 2:2-[1′-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-4′-fluoro-1′,2′,3′,4′,5′,6′-hexahydro-[2,4]bipyridinyl-5-yl]-propan-2-ol(Example 64)

This example is prepared from compound 36 and TFA following a proceduredescribed for example 63.

¹H-NMR (600 MHz, CDCl₃) δ=1.63 (6H, s), 2.05 (2H, m), 2.19 (3H, s), 2.32(3H, s), 2.55 (2H, m), 3.94 (4H, m), 4.53 (2H, b.s), 7.25 (5H, m), 7.59(1H, d, J=6 Hz), 7.90 (1H, m), 8.71 (1H, b.s).

HR MS (m/z, MH+) meas. 435.2554.

Piperazinyl-Pyridazines

Scheme 6 shows a general synthetic scheme for the preparation ofcompounds of Formula Ip. Substituted 1,4-dichloropyridazines II can bereacted with organo-zinc reagents under palladium catalysis to formintermediates XII. Displacement of the remaining chlorine with anpiperazine in the presence of base yields compounds XIII. Depending onthe position of substituent(s) Z the use of a N-protecting group mightbe required to block the reactivity of one of the piperazine nitrogens.Intermediates XIII can react depending on the desired linker Y withR3-Cl in a nucleophilic displacement reaction under basic conditions,with R—CHO in a reductive amination with e.g. NaBH(OAc)₃, in acylationreactions with R3-OC(O)Cl or R3-NCO, R3-COCl under basic conditions orwith R3-CO₂H in a amide coupling with e.g. HATU as coupling reagent toyield examples Ip. Additionally, displacement of the remaining chlorinein intermediate XII with a functionalized piperazine in the presence ofbase can yield directly examples Ip. (Route A). Alternatively, examplesIp can be prepared utilizing Route B and C in which the piperazinemoiety is first installed by nucleophilic displacement reactions and theNegishi coupling is performed subsequently.

Synthesis of Intermediates II and XII4,5-Dimethyl-1,2-dihydro-pyridazine-3,6-dione (Compound 36)

Hydrazine hydrochloride (58 g, 552 mmol) is dissolved in hot water (300mL) and dimethyl maleic anhydride (58 g, 460 mmol) is added in portionsand the suspension stirred at reflux for 16 h. The suspension is cooleddown to room temperature and the precipitate is filtered, washed withwater and dried at 40° C. under vacuum to yield4,5-dimethyl-1,2-dihydro-pyridazine-3,6-dione (36) (64 g, 99%).

¹H-NMR (400 MHz, DMSO-d₆) δ=11 (br s, 2H), 2.01 (s, 6H).

MS (m/z, MH+) meas. 141.1.

4,5-Dimethyl-1,4-dichloro-pyridazine (Compound 37)

4,5-dimethyl-1,2-dihydro-pyridazine-3,6-dione (50 g, 357 mmol) is addedto a 1 L flask and POCl₃ (250 mL) is slowly added. The suspension isstirred and heated to reflux and all starting material dissolves. After2 h approximately 150 mL POCl₃ are removed under vacuum. The viscous,brown solution is poured in small portions slowly onto ice in a 1.5 Lbeaker under stirring. The orange suspension is neutralized with 28%aqueous ammonia under external cooling. The product is filtered with aBuchner funnel, washed with water and dried at 40° C. under vacuum toyield a off white powder (59 g, 93%).

¹H-NMR (400 MHz, CDCl₃) δ=2.44 (s, 6H).

MS (m/z, MH+) meas. 177.1.

2,3,6,7-Tetrahydro-5H-cyclopenta[d]pyridazine-1,4-dione (Compound 38)

A solution of hydrazine hydrochloride (2.4 g, 22.8 mmol) and1-cyclopentene-1,2-dicarboxylic anhydride (3.0 g, 21.7 mmol) in water(10 mL) is heated to reflux for 3 h. The reaction mixture is cooled downto room temperature and the precipitate is collected by filtration. Theyellow solid is mixed with 15 mL 1N NaOH and stirred for 2 h, filteredand dried under vacuum to give2,3,6,7-tetrahydro-5H-cyclopenta[d]pyridazine-1,4-dione (38) (2.2 g,67%).

MS (m/z, MH+) meas. 153.1

1,4-Dichloro-6,7-dihydro-5H-cyclopenta[d]pyridazine (Compound 39)

The compound is prepared analogous to compound 37 starting from compound36.

¹H-NMR (400 MHz, DMSO-d₆) δ=2.74-2.61 (m, 4H), 2.00 (m, 1H), 1.85 (m,1H).

HR MS (m/z, MH+) meas. 188.9986.

2,3,5,6,7,8-Hexahydro-phthalazin-1,4-dione (Compound 40)

To a solution of hydrazine (392 μL, 13.1 mmol) in water (6 mL) and HOAc(2 mL) is added 4,5,6,7-tetrahydro-isobenzofuran-1,3-dione (2 g, 13.1mmol). The reaction mixture is refluxed for 3 h, then cooled down toroom temperature and the precipitate is collected by filtration, washedwith water and dried under vacuum to give2,3,5,6,7,8-hexahydro-phthalazin-1,4-dione (40) (2.09 g, 96%).

MS (m/z, MH+) meas. 167.05.

1,4-Dichloro-5,6,7,8-tetrahydro-phthalazine (Compound 41)

The suspension of compound 40 (2.09 g, 12.6 mmol) in POCl₃(10 mL) isrefluxed for 1 h, cooled down, and poured into ice. The precipitate iscollected by filtration and dried in a vacuum oven to give1,4-dichloro-5,6,7,8-tetrahydro-phthalazine (41) (2.23 g, 87%).

HR MS (m/z, MH+) meas. 203.0139.

3-Benzyl-6-chloro-4,5-dimethyl-pyridazine (Compound 42)

A mixture of 4,5-dimethyl-1,4-dichloro-pyridazine (10 g, 56.5 mmol),tetrakis(triphenylphosphine)palladium(0) (3.3 g, 2.80 mmol) and THF (200mL) is degassed and then benzylzinc bromide (147 mL, 0.5 M in THF, 73.40mmol) is added. The reaction solution is heated to 65° C. overnight.Solvent is removed. Water is added and the water layer is extracted withEtOAc. The organic layer is concentrated to afford a crude product thatis purified by chromatography on silica gel (EtOAc/Heptane: 0%˜50%) togive the title compound (9.5 g, 67%).

¹H NMR (400 MHz, CD₂Cl₂) δ=7.27 (m, 5H), 4.38 (s, 2H), 2.36 (s, 3H),2.21 (s, 3H).

HR MS (m/z, MH+) meas. 233.0839.

3-Chloro-6-(4-fluoro-benzyl)-4,5-dimethyl-pyridazine (Compound 43)

Analogous to compound 42 above,3-chloro-6-(4-fluoro-benzyl)-4,5-dimethyl-pyridazine is prepared from4,5-dimethyl-1,4-dichloro-pyridazine and para-fluoro benzyl zincbromide.

MS (m/z, MH+) meas. 251.1.

1-Benzyl-4-chloro-6,7-dihydro-5H-cyclopenta[d]pyridazine (Compound 44)

To a solution of 1,4-dichloro-6,7-dihydro-5H-cyclopenta[d]pyridazine(compound 39, 500 mg, 2.64 mmol) in THF (5 mL) is added Pd(PPh₃)₄ (383mg, 0.33 mmol). The mixture is degassed and benzyl zinc bromide (11 mL,0.5 M in THF, 5.6 mmol) is added. The mixture is heated at 60° C. for 5h. The reaction mixture is cooled down to RT and saturated aq. NaHCO₃solution is added and the mixture is extracted with EtOAc. The combinedorganic layers are washed with water, brine, dried over NaSO₄, filteredand concentrated. The crude product is purified by flash chromatography(EtOAc/heptane 10%-30%) to give compound 44 (490 mg, 76%).

¹H-NMR (400 MHz, CD₂Cl₂) δ=7.30-7.21 (m, 5H), 4.28 (s, 2H), 2.97 (m,2H), 2.84 (m, 2H), 2.09 (m, 2H).

HR MS (m/z, MH+) meas. 245.0848.

1-Chloro-4-(4-fluoro-benzyl)-6,7-dihydro-5H-cyclopenta[d]pyridazine(Compound 45)

Compound 45 is prepared analogous to compound 44 starting from of1,4-dichloro-6,7-dihydro-5H-cyclopenta[d]pyridazine (compound 39) andpara-fluorobenzyl zinc bromide.

¹H-NMR (400 MHz, CD₂Cl₂) δ=7.23 (m, 2H), 6.99 (m, 2H), 4.27 (s, 2H),2.98 (m, 2H), 2.84 (m, 2H), 2.11 (m, 2H).

HR MS (m/z, MH+) meas. 263.0752.

1-Chloro-4-(4-fluoro-benzyl)-5,6,7,8-tetrahydro-phthalazine (Compound46)

To a solution of 1,4-dichloro-5,6,7,8-tetrahydro-phthalazine (compound41, 0.50 g, 2.46 mmol) in THF (5 mL) are added 4-fluoro-benzylzincchloride (0.5M in THF) (6.40 mL, 3.20 mmol) and palladium tetrakistriphenylphosphine (0.36 g, 0.31 mmol). The mixture is degassed andstirred at 50° C. overnight. Then the reaction mixture is cooled down toroom temperature, sat. NaHCO₃ and water are added and the mixture isextracted with EtOAc. The combined organic layers are washed with brine,dried over Na₂SO₄, filtered and concentrated down. The crude product ispurified by chromatography (EtOAc/heptane: 10%˜40%) to give1-chloro-4-(4-fluoro-benzyl)-5,6,7,8-tetrahydro-phthalazine (46) (0.51g, 30%).

MS (m/z, MH+) meas. 277.11.

Synthesis of Intermediates XIII

General Protocol for the Amination of Chlorides XII with Piperazines toYield Compounds 48-53 (Route A)

To a solution of XII (0.4 mmol) in NMP or DMF/dioxane (2 mL) is addedthe piperazine (0.6 mmol). The reaction mixture is heated at 190° C. for4 h in a microwave reactor. It is cooled down to rt, diluted with DCM,washed with aq. NaHCO₃ solution and the organic layers are removed toafford the crude product. Flash chromatography of the crude product withEtOAc/heptane (20% to 50%) and then MeOH/DCM (5% to 20%) provides theproduct as a yellow solid after removal of the solvents (˜50%-70%)

3-Benzyl-4,5-dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazine(Compound 47)

Preparation A:

3-Chloro-4,5-dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazine (400mg, 1.66 mmol, 1 eq) is added to a solution of benzylzinc bromide (12.3mL 0.5 M in THF, 6.64 mmol, 4 eq) andtetrakis(triphenylphosphine)palladium (100 mg, 0.08 mmol, 0.05 eq) in amicrowave vial. The vial is sealed and irradiated in the microwave at100° C. (high absorption setting) for 40 min. The reaction mixture isconcentrated and purified by silica gel chromatography (5-20%EtOAc/heptane) to yield the desired compound (324 mg, 66%).

Preparation B:

To a solution of 3-benzyl-6-chloro-4,5-dimethyl-pyridazine (100 mg, 0.41mmol) in NMP (2 mL) is added 2-(R)-methyl-piperazine (62 mg, 0.61 mmol).The reaction mixture is heated at 190° C. for 411 in a microwavereactor. It is cooled down to rt, diluted with DCM, washed with aq.NaHCO₃ solution and the organic layers are removed to afford the crudeproduct. Flash chromatography of the crude product with EtOAc/heptane(20% to 50%) and then MeOH/DCM (5% to 20%) provides the product as ayellow solid after removal of the solvents (74 mg, 61%).

¹H NMR (400 MHz, DMSO-d₆) δ=7.22-7.34 (m, 2 H), 7.11-7.22 (m, 3 H), 4.22(s, 2 H), 3.13-3.26 (m, 2 H), 2.81-2.99 (m, 3 H), 2.70-2.80 (m, 1 H),2.38-2.48 (m, 1 H), 2.15 (s, 3 H), 2.08 (s, 3 H), 1.00 (d, J=6.5 Hz, 3H).

HR MS (m/z, MH+) meas. 297.2089.

Compound 46-53

The following table (Table 4) lists compounds prepared by amination asdescribed above:

TABLE 4 HR MS [m/z, Compound Structure MH+] meas. 48

283.1918 49

294.4028 50

308 (MS) 51

326 (MS) 52

297.2088 53

311.5 (MS)Intermediates from Route B:

3-Chloro-4,5-dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazine(Compound 54)

Solid K₂CO₃ (10 g, 72.4 mmol, 1.8 eq) is added to a solution of(R)-2-methyl-piperazine (4.00 g, 40 mmol, 1 eq) and3,6-dichloro-4,5-dimethyl-pyridazine (8 g, 45.2 mml, 1.1 eq) in DMF (50mL), and the resulting solution is stirred at 60° C. for 48 h. Thereaction mixture is concentrated to ½ volume under reduced pressure andthe minimum water (ca. 15 mL) required to dissolve the solid salts isadded, followed by the addition of dichloromethane (100 mL). The organiclayer is separated, dried over sodium sulfate and concentrated underreduced pressure, then purified by silica gel column chromatography(2%-20% MeOH/CH₂Cl₂) to yield the desired compound as a white solid (4.7g, 49%).

¹H NMR (400 MHz, CDCl₃) δ=3.08-3.21 (m, 2H), 2.73-2.92 (m, 4H,) 2.47(dd, J=12.4 Hz, 10.2 Hz, 1H), 2.13 (s, 3H), 2.07 (s, 3H), 0.93 (d, J=6.3Hz, 3H).

HR MS (m/z, MH+): meas. 241.1218.

3-Chloro-4,5-dimethyl-6-(piperazin-1-yl)-pyridazine (Compound 55)

Compound 55 is prepared as described above from piperazine and3,6-dichloro-4,5-dimethyl-pyridazine.

MS (m/z, MH+) meas. 227.

(R)-4-(6-Chloro-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (Compound 56)

3-Chloro-4,5-dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazine (1.20g, 4.88 mmol), 5-chloro-pyrazine-2-carboxylic acid methyl ester (946 mg,5.37 mmol), triethylamine (3.40 mL, 24.4 mmol), and 1,4-dioxane (10 mL)are combined in a 100 mL round-bottom flask fitted with a refluxcondenser and heated to 80° C. for 24 h. The reaction is then allowed tocool to room temperature and stirred for 48 h. A beige solidprecipitates during this time which is isolated by filtration, rinsingwith H₂O. The precipitate is dried in vacuo to afford the title compound(1.30 g, 71%).

MS (m/z, MH+) meas. 377.3.

2-[(R)-4-(6-Chloro-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol(Compound 57)

(R)-4-(6-Chloro-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (400 mg, 1.04 mmol) is suspended in THF (12 mL) andcooled to −78° C. Methylmagnesium iodide (2.8 mL, 3 M in diethyl ether,8.4 mmol) is added dropwise. The reaction is stirred for 30 min, warmedto 0° C., and stirred an additional 30 min. Sat. aq. NH₄Cl (10 mL) isadded to quench, followed by additional H₂O (40 mL). The organics areextracted with EtOAc (3×50 mL), dried and concentrated to give thedesired product as a beige powder (415 mg, quant.).

MS (m/z, MH+) meas. 359.3.

2-[(R)-4-(6-Chloro-4,5-dimethyl-pyridazin-3-yl)-2-methyl-piperazin-1-yl]-4-trifluoromethyl-pyrimidine-5-carboxylicacid methyl ester (Compound 58)

Triethylamine (2.0 mL, 14.4 mmol, 2.9 eq) is added to a solution of2-chloro-4-trifluoromethyl-pyrimidine-5-carboxylic acid methyl ester(1.25 g, 5.0 mmol, 1 eq),3-chloro-4,5-dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazine (1.20g, 5.0 mmol, 1 eq) in dichloromethane (40 mL) and the resulting solutionis stirred at rt for 2 h. The reaction mixture is diluted withdichloromethane (50 mL) and washed with water (25 mL), then brine (25mL). The organic layer is separated, dried over sodium sulfate andconcentrated under reduced pressure to a white residue. The desiredcompound is isolated by silica gel chromatography (10-75% EtOAc/heptane)as a white solid (1.83 g, 82%).

¹H NMR (400 MHz, DMSO-d₆) δ=9.00 (s, 1H), 4.92-5.15 (m, 1H), 4.54-4.76(m, 1H), 3.84 (s, 3H), 3.59 (d, J=14.0 Hz, 1H), 3.50 (t, J=12.8 Hz, 2H),3.08 (dd, J=12.8 Hz, 3.3 Hz, 1H), 2.89-2.99 (m, 1H), 2.36 (s, 3H), 2.33(s, 3H), 1.39 (d, J=7.0 Hz, 3H).

HR MS (m/z, MH+): meas. 445.1373.

2-[(R)-4-(6-Chloro-4,5-dimethyl-pyridazin-3-yl)-2-methyl-piperazin-1-yl]-4-trifluoromethyl-pyrimidine-5-carboxylicacid ethyl ester (Compound 59)

Following the protocol above with2-chloro-4-trifluoromethyl-pyrimidine-5-carboxylic acid ethyl ester (400mg, 1.57 mmol, 1 eq) and3-chloro-4,5-dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazine (400mg, 1.66 mmol, 1 eq) affords 700 mg of desired product as a white solid(97%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.94 (s, 1 H), 5.12-5.18 (m, 1H), 4.70-4.85(m, 1H), 4.35 (q, J=7.0 Hz, 2H), 3.48-3.56 (m, 2H), 3.40 (d, J=12.5 Hz,1H), 3.21 (d, J=10.5 Hz, 1H), 3.02-3.14 (m, 1H), 2.36 (s, 3H), 2.35 (s,3H), 1.44 (d, J=7.0 Hz, 3H), 1.37 (t, J=7.0 Hz, 3H).

3-Chloro-4,5-dimethyl-6-[(R)-3-methyl-4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazine(Compound 60)

Combine 3,6-dichloro-4,5-dimethyl-pyridazine (100 mg, 0.554 mmol),(R)-2-methylpiperazine (85 mg, 0.831 mmol), potassium carbonate (383 mg,2.77 mmol) and DMF (1 mL) in vial. Heat in the microwave at 120° C. for3.25 h. Add 2-chloro-5-trifluoromethylpyridine (181 mg, 0.997 mmol) andheat at 180° C. for 30 min. The crude reaction is purified directly byflash chromatography on silica gel (0-40% EtOAc in heptanes) to affordthe title compound as a light yellow solid (78 mg, 37%).

MS (m/z, MH+) meas. 386.4

Intermediates from Route C:

3-Chloro-4,5-dimethyl-6-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazine(Compound 61)

1-(5-Trifluoromethyl-pyridin-2-yl)-piperazine (10 g, 43.3 mmol) iscombined with 3,6-dichloro-4,5-dimethyl-pyridazine (14.4 g, 84.3 mmol),triethylamine (8.25 mL), and NMP (40 mL). The reaction mixture isirradiated to a temperature of 180° C. for 25 min, and then concentratedin vacuo. The residue is purified by flash chromatography on silica gel(0-8% MeOH/CH₂Cl₂) to afford the title compound (13.2 g, 82%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.48-8.41 (m, 1H), 7.84 (dd, J=9.1 Hz, 2.4Hz, 1H), 7.03 (d, J=9.1 Hz, 1H), 3.88-3.76 (m, 4H), 3.28-3.20 (m, 4H),2.31 (s, 6H).

1-Chloro-4-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-6,7-dihydro-5H-cyclopenta[d]pyridazine(Compound 62)

To a solution of 4-dichloro-6,7-dihydro-5H-cyclopenta[d]pyridazine(compound 39, 500 mg, 2.64 mmol) in NMP (5 mL) is added1-[5-trifluoromethyl)-pyrid-2-yl)-piperazine (581 mg, 2.51 mmol)followed by triethyl amine (1.1 mL, 7.9 mmol). The mixture was heated ina microwave reactor for 170° C. for 60 min. Water was added to thereaction mixture and extracted with EtOAc. The combined organic extractswere washed with water, brine, dried over Na₂SO₄, filtered andconcentrated. The crude product was tritirated with methanol to providethe title compound (483 mg, 48%).

¹H NMR (CD₂Cl₂) δ=8.41 (s, 1H), 7.68 (dd, J=8.9 Hz, 2.5 Hz, 1H), 6.73(d, J=8.9 Hz, 1H), 3.80 (m, 4H), 3.60 (m, 4H), 3.04 (m, 2H), 2.95 (m,2H), 2.16 (m, 2H).

HR MS (m/z, MH+): meas. 384.1190.

1-Chloro-4-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-5,6,7,8-tetrahydro-phthalazine(Compound 63)

To a solution of 1,4-dichloro-5,6,7,8-tetrahydro-phthalazine (compound25, 100 mg, 0.492 mmol) in NMP (3 mL) is added1-[5-trifluoromethyl)-pyrid-2-yl)-piperazine (114 mg, 0.492 mmol)followed by triethyl amine (218 μL, 1.57 mmol). The mixture was heatedin a microwave reactor for 140° C. for 60 min. Water was added to thereaction mixture and extracted with EtOAc. The combined organic extractswere washed with water, brine, dried over Na₂SO₄, filtered andconcentrated. The crude product was purified by flash chromatography onsilica gel (EtOAc/heptane 10% to 70%) to yield 96 mg (49%) of the titlecompound.

¹H NMR (400 MHz, CD₂Cl₂) δ=8.41 (s, 1H), 7.73 (dd, J=9.0 Hz, 2.5 Hz,1H), 6.79 (d, J=9.0 Hz, 1H), 3.85 (m, 4H), 3.40 (m, 4H), 2.76-2.68 (m,4H), 1.93 (m, 2H), 1.80 (m, 2H).

HR MS (m/z, MH+) meas. 398.1359.

6-[4-(4-Chloro-5,6,7,8-tetrahydro-phthalazin-1-yl)-piperazin-1-yl]-nicotinicacid ethyl ester (Compound 64)

The compound is prepared in a similar fashion as described above.

MS (m/z, MH+) meas. 402.2

6-[(S)-4-(4-Chloro-6,7-dihydro-5H-cyclopenta[d]pyridazin-1-yl)-3-methyl-piperazin-1-yl]-nicotinicacid methyl ester (Compound 65)

To a solution of 1,4-dichloro-6,7-dihydro-5H-cyclopenta[d]pyridazine(150 mg, 0.79 mmol) in NMP (5 mL) is added(S)-3-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylic acidethyl ester (297 mg, 1.19 mmol) and triethyl amine (332 μL, 2.39 mmol).The reaction mixture is heated in a microwave reactor at 195° C. for 4h. Water and EtOAc is added. The layers are separated and the aqueouslayer is extracted with EtOAc. The combined organic layers are washedwith water, brine, dried over Na₂SO₄, filtered and concentrated. Thecrude product is purified by flash chromatography (EtOAx/heptane 10% to70%) to yield 50 mg (16%) of the title compound.

4-(6-Chloro-4,5-dimethyl-pyridazin-3-yl)-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (Compound 66)

To the solution of 3,4,5,6-tetrahydro-2H-[1,2]bipyrazinyl-5′-carboxylicacid methyl ester (250 mg, 1.07 mmol) in NMP (5 mL) is added3,6-dichloro-4,5-dimethyl-pyridazine (237 mg, 1.33 mmol) and TEA (446μl, 3.21 mmol), the reaction mixture is stirred at 190° C. for 60 min.Water is added to the mixture and extracted with EtOAc. The combinedorganic layers are washed with water, brine, dried over Na₂SO₄, filteredand concentrated. The crude product is purified by HPLC,(acetonitrile/water: 10%˜95% with 3% 1-propanol) to give white powder(165 mg, 43%).

¹H-NMR (400 MHz, DMSO-d₆) δ=8.69 (s, 1H), 8.44 (s, 1H), 3.92 (t, J=5.0Hz, 4H), 3.83 (s, 3H), 3.27 (m, 4H), 2.41 (s, 3H), 2.32 (s, 3H).

MS (m/z, MH+) meas. 363.

Synthesis of Examples 65-72

General Protocol for the Negishi Coupling of Pyridazine Chlorides IIIawith Aryl Zinc Bromides to Yield Examples 65-69 (Route B/C)

To a solution of chloropyridazine IIIa (0.15 mmol, 1 eq.) in THF (5 ml)is added Pd(PPh₃)₄ (12.5 mol %). The mixture is degassed and arylzincbromide (0.225, 1.5 eq., e.g. as a 0.5 M solution in THF) is addedand the mixture is heated in a microwave reactor at 80° C. for 30 min.The reaction mixture is cooled to rt, water is added and the mixture isextracted with EtOAc. The combined organic extracts are washed withwater, brine, dried over sodium sulfate, filtered and concentrated. Thecrude product is purified by flash chromatography on silica gel withEtOAc/heptane as eluent to yield examples Ip.

The following table (Table 5) lists compounds prepared by Negishicoupling as described above:

TABLE 5 HR MS [m/z, Example Structure MH+] meas. 65

474.1670 66

476.1865 67

458.1974 68

454.2226 69

492 (MS)

Example 702-(6-{(S)-4-[4-(2-Chloro-benzyl)-6,7-dihydro-5H-cyclopenta[d]pyridazin-1-yl]-3-methyl-piperazin-1-yl}-pyridin-3-yl)-propan-2-ol

To a solution of(S)-4-[4-(2-chloro-benzyl)-6,7-dihydro-5H-cyclopenta[d]pyridazin-1-yl]-3-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid ethyl ester (35 mg, 0.071 mmol) in THF (5 mL) is added methylmagnesium iodide (3 M in ether, 0.19 mL, 0.57 mmol) at 0° C. and themixture is stirred at rt for 30 min. Sat. NaHCO₃ solution and EtOAc isadded. The layers are separated and the aqueous layer is extracted withEtOAc. The combined organic layers are washed with water, brine, driedover Na₂SO₄, filtered and concentrated. The crude product is purified byHPLC (acetonitrile/water with 0.1% TFA, 10% to 50%). The product isisolated as the free base after treatment of the salt with Na₂CO₃solution (11 mg, 32%)

HR MS (m/z, MH+) meas. 478.2367.

Example 712-{(R)-4-[6-(2,4-difluoro-benzyl)-4,5-dimethyl-pyridazin-3-yl]-2-methyl-piperazin-1-yl}-4-trifluoromethyl-pyrimidine-5-carboxylicacid ethyl ester

To a solution of2-[(R)-4-(6-chloro-4,5-dimethyl-pyridazin-3-yl)-2-methyl-piperazin-1-yl]-4-trifluoromethyl-pyrimidine-5-carboxylicacid ethyl ester (229 mg, 0.50 mmol, 1 eq) and THF (1.4 mL) in amicrowave vial is added 2,4-difluorobenzylzinc bromide (2.0 mL 0.5 Msolution in THF, 2.0 mmol, 4 eq) andtetrakis(triphenylphosphine)palladium (25 mg, 0.03 mmol, 0.05 eq). Thevial is sealed and heated in the microwave at 60° C. (high absorptionsetting) for 25 min. An additional aliquot of 2,4-diflorobenzylzincbromide (1.0 mL 0.5 M solution in THF, 1.0 mmol, 2 eq) is added and thereaction mixture is heated in the microwave at 100° C. (high absorptionsetting) for 5 min. The reaction mixture is quenched with water (10 mL)and then extracted with EtOAc (2×25 mL). The combined organic fractionsare dried over magnesium sulfate, concentrated and purified by silicagel chromatography (25-75% EtOAc/Heptane) to yield the desired compound(225 mg, 81%).

¹H NMR (400 MHz, CDCl₃) δ=8.86 (s, 1H), 7.12 (t, J=7.3 Hz, 1H),6.76-6.83 (m, 2H), 4.99-5.07 (m, 1H), 4.64-4.73 (m, 1H), 4.28 (q, J=7.0Hz, 2H), 3.35-3.46 (m, 2H), 3.31 (d, J=12.5 Hz, 1H), 3.10 (d, J=10.5 Hz,1H), 2.90-3.02 (m, 1H), 2.25 (s, 3H), 2.24 (s, 3H), 1.36 (d, J=7.0 Hz,3H), 1.29 (t, J=7.0 Hz, 3H).

Example 722-(2-{(R)-4-[6-(2,4-Difluoro-benzyl)-4,5-dimethyl-pyridazin-3-yl]-2-methyl-piperazin-1-yl}-4-trifluoromethyl-pyrimidin-5-yl)-propan-2-ol

To a solution of2-{(R)-4-[6-(2,4-difluoro-benzyl)-4,5-dimethyl-pyridazin-3-yl]-2-methyl-piperazin-1-yl}-4-trifluoromethyl-pyrimidine-5-carboxylicacid ethyl ester (220 mg, 0.40 mmol, 1 eq) in THF (1.0 mL), cooled in anice bath, is added a solution of MeMgBr (2 mL, 3 M in ether, 6 mmol, 15eq.). The solution is allowed to warm to rt for 30 min. The reaction isquenched with the careful addition of saturated NH₄Cl, then extractedwith EtOAc. The organic layer is dried over sodium sulfate, thenconcentrated. The product is isolated by silica gel columnchromatography (25-75% EtOAc/heptane) to yield the desired compound as awhite solid (27 mg, 13%).

¹H NMR (400 MHz, CDCl₃) δ=8.74 (s, 1H), 7.21 (tt, J=8.3 Hz, 6.5 Hz, 1H),6.85-6.94 (m, 1H), 4.95-5.05 (m, 1H), 4.64 (dd, J=12.5 Hz, 3.3 Hz, 1H),4.26 (s, 2H), 3.49 (d, J=12.4 Hz, 1H), 3.36-3.44 (m, 2H), 3.19 (dd,J=12.5 Hz, 3.8 Hz, 1H), 3.05 (td, J=12.0 Hz, 3.3 Hz, 1H), 2.35 (s, 3H),2.33 (s, 3H), 1.70 (s, 6H), 1.42 (d, J=6.7 Hz, 3 H).

HR MS (m/z, MH+) meas. 537.2408.

Synthesis of Examples 73-87

General Protocol for the Amination of Aromatic Chlorides with AminesXIII to Yield Examples 74 to 86 (Route A)

To a solution of amine XIII (0.5 mmol, 1 eq.) and the aromatic halide (1mmol, 2 eq.) in NMP (2.5 ml) is added triethylamine (1.5 mmol, 3 eq.).The mixture is heated in a microwave reactor to temperatures between140° C. and 190° C. (depending on the reactivity of the aromatic halide)for 30 min. After LC MS shows completion of the reaction, water andEtOAc is added and the layers are separated and the aqueous layer isextracted with EtOAc. The combined organic layers were washed withwater, brine, dried over sodium sulfate, filtered and concentrated. Theproduct is purified by flash chromatography on silica gel withEtOAc/heptane as eluent to yield examples Ip.

Example 73(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2]bipyrazinyl-5′-carboxylicacid methyl ester

A mixture of compound 47 (6.0 g, 20.27 mmol),5-chloropyrazine-2-carboxylic acid methyl ester (5.3 g, 30.30 mmol),Et₃N (6.2 g, 60.60 mmol) and dioxane (100 mL) is heated to refluxovernight. Solvent is removed. Saturated NH₄Cl solution is added andextracted with EtOAc. The organic layer is concentrated to afford thecrude product that is purified by chromatography on silica gel(EtOAc/heptane: 50%˜100%) to give the title compound (6.6 g, 76%) as ayellow solid.

¹H NMR (400 MHz, CD₂Cl₂) δ=8.81 (s, 1H), 8.21 (s, 1H), 7.29 (m, 5H),4.83 (m, 1H), 4.43 (m, 1H), 4.33 (s, 2H), 3.94 (s, 3H), 3.52 (m, 3H),3.27 (m, 1H), 3.14 (m, 1H),), 2.31 (s, 3H), 2.17 (s, 3H), 1.49 (d, J=6.5Hz, 3H).

HR MS (m/z. MH+) meas. 433.2348.

Examples 74-86

The following table (Table 6) lists examples of compounds prepared byamination as described in the general procedure:

TABLE 6 Example Structure HR MS [m/z, MH+] meas. 74

419 (MS) 75

433.2341 76

447.6 (MS) 77

431 (MS) 78

445.2353 79

417.4825 80

513.2225 81

519.2140 82

501.2207 83

515.2383 84

463 (MS) 85

512 (MS) 86

530 (MS)

Example 873-Benzyl-4,5-dimethyl-6-[(R)-3-methyl-4-(4-trifluoro-methanesulfonylphenyl)-piperazin-1-yl]-pyridazine

To the solution of3-benzyl-4,5-dimethyl-6-((R)-3-methyl-piperazin-1-yl)-pyridazine (80 mg,0.257 mmol) in dioxane (5 mL) is added1-chloro-4-trifluoromethanesulfonyl-benzene (95.2 mg, 0.385 mmol),potassium hydroxide pellets (101 mg, 1.55 mmol), naphthoquinoneimidazolin-2-ylidene-Pd(0) (175 mg, 0.129 mmol). The mixture is heatedin a microwave reactor at 100° C. for 120 min. Water is added to themixture and extracted with EtOAc. The combined organic layers are washedwith water, brine, dried over Na₂SO₄, filtered and concentrated down.The crude product is purified by HPLC (acetonitrile/water: 10%˜95% with3% 1-propanol), to give a light yellow colored powder (55 mg, 89%).

¹H-NMR (400 MHz, DMSO-d₆) δ=7.81 (d, J=9.1 Hz, 2H), 7.17-7.30 (m, 7H),4.51 (m, 1H), 4.26 (s, 2H), 3.97 (d, J=12.6 Hz, 1H), 3.55 (d, J=12.2 Hz,1H), 3.42 (m, 2H), 3.14 (m, 1H), 3.00 (m, 1H), 2.26 (s, 3H), 2.13 (s,3H), 1.31 (d, J=6.5 Hz, 3H).

HR MS (m/z, MH+) meas. 505.1872 calc. 505.1885.

Synthesis of Examples 88-115

General Protocol for the Grignard Reaction with Esters

To a solution of the ester (0.5 mmol, 1 eq.) in THF (3 mL) is addedalkyl magnesium bromide or iodide (4 mmol, 8 eq., solution in ether) at−78° C. The reaction mixture is stirred at 0° C. for 2 h then dilutedwith DCM and washed with NH₄Cl and water. The combined organic layersare washed with water, brine, dried over Na₂SO₄, filtered andconcentrated down. Purification by HPLC of the crude product withacetonitrile in water provides the tertiary alcohols (main product) nextto smaller amounts of the corresponding methyl ketones. The solvents areremoved with a lyophilizer to provide the products as white powders.

Example 882-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol

To a solution of(R)-4-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (840 mg, 1.85 mmol) in THF (12 mL) is added methylmagnesium bromide (5 mL, 15 mmol, 3M in ether) at −78° C. The reactionmixture is stirred at 0° C. for 2 h then diluted with DCM and washedwith NH₄Cl and water. The combined organic layers are washed with water,brine, dried over Na₂SO₄, filtered and concentrated down. Purificationby HPLC of the crude product with acetonitrile in water (from 10% to 95%with 3% 1-propanol) at 220 nm wavelength detection provides the desiredalcohol (400 mg, 50%) next to small amounts of the corresponding methylketone (example 95). The solvents are removed with a lyophilizer toprovide the products as white powders.

¹H NMR (400 MHz, CD₂Cl₂) δ=8.28 (s, 1H), 8.10 (s, 1H), 7.25 (m, 5H),4.83 (m, 1H), 4.33 (s, 2H), 4.20 (m 1H), 3.78 (s, 1H), 3.57 (m, 1H),3.44 (m, 2H), 3.29 (m, 1H), 3.14 (m, 1H), 2.31 (s, 3H), 2.16 (s, 3H),1.56 (s, 6H), 1.40 (d, J=6.5 Hz, 3H).

HR MS (m/z, MH+) meas. 433.2713, calc. 433.2716.

Examples 89-111

The following table (Table 7) lists examples of compounds prepared byGrignard addition as described above:

TABLE 7 Example Structure HR MS [m/z; MH+] meas. 89

419.2546 90

433.2716 91

447.2865 92

421.2559 93

445.2710 94

431.5 (MS) 95

417.2395. 96

501.2599 97

519.2485 98

513.2584 99

531.2509 100

485.2271 101

503.2163 102

497.2258 103

515 (MS) 104

462.2679 105

448.2250 106

436.2532 107

512 (MS) 108

496 (MS) 109

530.2543 110

514.2247 111

461.3036

Example 1122-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-2,2-dimethoxy-ethanol

To a solution of KOH (33 mg, 0.38 mmol) and methanol (5 mL) is addedexample 95 (20 mg, 0.048 mmol) in methanol (1 mL) and then iodobenzenediacetate (23 mg, 0.072 mmol) in portions at 0° C. The mixture isstirred at rt overnight. Solvent is removed to give a crude product thatis purified by HPLC (acetonitrile/water (1% NH₄OH), 30%˜100%) to givethe title compound (12 mg, 52%) as a yellow solid.

¹H NMR (400 MHz, CD₂Cl₂) δ=8.42 (s, 1H), 8.18 (s, 1H), 7.29 (m, 5H),4.72 (m, 1H), 4.32 (s, 2H), 4.30 (m, 1H), 3.94 (d, J=6.0 Hz, 2H), 3.58(m, 1H), 3.47 (m, 2H), 3.28 (m, 1H), 3.26 (s, 6H), 3.13 (m, 1H), 2.31(s, 3H), 2.16 (s, 3H), 1.44 (d, J=6.5 Hz, 3H).

Example 1131-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-ethanol

To a solution of example 95 (50 mg, 0.12 mmol) and MeOH (3 mL) is addedNaBH₄ (10 mg, 0.24 mmol) at 0° C., afterwards the reaction mixture isstirred at rt an additional 0.5 h. Solvent is removed and water isadded, then extracted with DCM. The organic layer is concentrated toafford the title compound (38 mg, 76%) as a white solid.

¹H NMR (400 MHz, CD₂Cl₂) δ=8.04 (s, 1H), 8.01 (s, 1H), 7.15 (m, 5H),4.73 (m, 1H), 4.57 (m, 1H), 4.21 (s, 2H), 4.07 (m, 1H), 3.46 (m, 1H),3.33 (m, 2H), 3.15 (m, 1H), 3.01 (m, 2H), 2.19 (s, 3H), 2.05 (s, 3H),1.39 (d, J=6.5 Hz, 3H), 1.30 (d, J=6.5 Hz, 3H).

HR MS (m/z, MH+) meas. 419.2543.

Example 1141-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl)-2-hydroxy-ethanone

To a solution of KOH (224 mg, 4.0 mmol) and CH₃OH (10 mL) is added1-[(R)-4-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl)-ethanone(400 mg, 1.0 mmol) in CH₃OH (10 mL) and then iodobenzene diacetate (464mg, 1.5 mmole) in portions at 0° C. The mixture is stirred at roomtemperature overnight. The solvent is removed and then extracted withDCM. The organic layer is washed with aqueous NH₄Cl and afterwardsconcentrated to yield crude example 112. This material is dissolved inwater and then 6 N HCl (5 mL) is added. The mixture is stirred at roomtemperature for 3 h. Afterwards it is made basic with NaHCO₃ andextracted with DCM. The organic layer is concentrated to give a crudeproduct that is purified by chromatography on silica gel (EtOAc/Heptane:50%˜100%) to give the title compound (240 mg, 58%) as a yellow solid.

¹H NMR (400 MHz, CD₂Cl₂) δ=8.82 (s, 1H), 8.15 (s, 1H), 7.27 (m, 5H),4.91 (s, 2H), 4.86 (m, 1H), 4.48 (m, 1H), 4.33 (s, 2H), 3.57 (m, 2H),3.46 (m, 1H), 3.30 (m, 2H), 3.14 (m, 1H), 2.31 (s, 3H), 2.17 (s, 3H),1.50 (d, J=6.5 Hz, 3H).

HR MS (m/z, MH+) meas. 433.2340.

Example 1151-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl)-ethane-1,2-diol

To a solution of1-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl)-2-hydroxy-ethanone(example 114, 110 mg, 0.25 mmol) and EtOH (20 ml) is added NaBH₄ (14 mg,0.38 mmol) at 0° C. The mixture is warmed up to room temperature andstirred for 3 h. The reaction solution is acidified with 3N HCl to pH ˜7and the organic solvent is removed. The residue is dissolved insaturated NaHCO₃ solution and extracted with DCM. The organic layer isconcentrated to afford the title compound (96 mg, 91%) as a white solid.

¹H NMR (400 MHz, CD₂Cl₂) δ=8.09 (s, 1H), 8.00 (s, 1H), 7.18 (m, 5H),4.64 (m, 1H), 4.57 (m, 1H), 4.26 (s, 2H), 4.10 (m, 1H), 3.60 (m, 2H),3.48 (m, 1H), 3.34 (m, 2H), 3.18 (m, 1H), 3.02 (m, 1H), 2.21 (s, 3H),2.06 (s, 3H), 1.30 (d, J=6.5 Hz, 3H).

HR MS (m/z, MH+) meas. 435.2511.

Synthesis of examples 116 and 117 Example 116(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid

(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methyl ester (1.8 g, 4.16 mmol) is combined with LiOH (998 mg, 42mmol), H₂O (20 mL), THF (20 mL), and MeOH (10 mL). The combined mixtureis allowed to stir at room temperature for 16 h. It is concentrated toremove organic solvents in vacuo. Additional water is added and the pHis adjusted to 4.0 with HCl or phosphate buffer. The solution isextracted with EtOAc and the combined organic extracts are washed withbrine. The extract is dried over sodium sulfate and filtered to removethe drying agent. The filtrate is concentrated to afford the titlecompound (1.46 g, 84%).

¹H NMR (400 MHz, CD₂Cl₂) δ=8.89 (s, 1H), 8.10 (s, 1H), 7.27 (m, 5H),4.84 (m, 1H), 4.44 (m, 1H), 4.34 (s, 2H), 3.58 (m, 3H), 3.31 (m, 1H),3.16 (m, 1H), 2.32 (s, 3H), 2.18 (s, 3H), 1.50 (d, J=6.5 Hz, 3H).

HR MS (m/z, MH+) meas. 419.2200.

Example 1172-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-piperazin-1-yl]-4-trifluoromethyl-pyrimidine-5-carboxylicacid

To a solution of methyl2-[(R)-4-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-piperazin-1-yl]-4-trifluoromethyl-pyrimidine-5-carboxylate(500 mg, 1.0 mmol, 1.0 eq) in THF (5 mL) is added an aqueous solution ofLiOH (1 M, 2.0 mL, 2.0 mmol, 2.0 eq) and the resulting solution isheated to 75° C. for 4 h. The reaction mixture is diluted with EtOAc (50mL) and washed with water (3×15 mL). The combined aqueous washes wereadjusted to pH 6 with aqueous HCl (1 M), then extracted withdichloromethane (3×50 mL). The combined organic layers are dried oversodium sulfate and concentrated under reduced pressure to yield thedesired product as a white solid (470 mg, 96%).

¹H NMR (400 MHz, MeOH-d₄) δ=8.97 (s, 1H), 7.23-7.30 (m, 2H), 7.10-7.22(m, 3H), 5.11-5.23 (m, 1H), 4.77-4.86 (m, 1H), 4.31 (s, 2H), 3.52-3.64(m, 2H), 3.50 (d, J=12.5 Hz, 1H), 3.17 (dd, J=12.5 Hz, 3.5 Hz, 1H),2.97-3.09 (m, 1H), 2.37 (s, 3H), 2.17 (s, 3H), 1.47 (d, J=6.5 Hz, 3H).

HR MS (m/z, MH+) meas. 487.2088.

Synthesis of examples 118-144

General Protocol for the Amide Formation with Acid Example 116 to YieldFurther Examples 118 to 140

Method A:

A mixture of example 116 (40 mg, 0.10 mmol) and SOCl₂ (10 mL) is heatedto reflux for 1 h and then solvent is removed. The residue is dissolvedin DCM (2 mL) and transferred to a solution of amine (0.14 mmole) andDCM (3 mL). The reaction mixture is stirred at rt for 2 h. Water (10 mL)is added and the mixture extracted with DCM (3×20 mL). The organic layeris concentrated to give a crude product that is purified by HPLC[acetonitrile/water (1% NH₄OH), 30%˜100%] to afford the product(examples 118 to 132, 20%˜84%).

Method B:

A mixture of example 116 (40 mg, 0.10 mmol), HATU (73 mg, 0.14 mmole),diisopropylethyl amine (37 mg, 0.29 mmol), dimethylacetamide (1.5 ml)and amine (0.14 mmole) is stirred at rt for 10 h. The crude product ispurified by HPLC (acetonitrile/water (3% propanol), 30%˜100%) to affordthe product (examples 133 to 140, 37%˜55%).

Examples 118-140

The following table (Table 8) lists examples of compounds prepared byamide formation as described above:

TABLE 8 Example Structure HR MS [m/z, MH+] meas. 118

516.3076 119

460.2810 120

501.3091 121

486.2969 122

529.3404 123

476.2772 124

515.3204 125

530.3240 126

488.2773 127

492.2732 128

458.2668 129

502.2933 130

490.2907 131

501.2723 132

476.2763 133

474.2962 134

500.2369 135

490.2918 136

476.2776 137

531.3190 138

523.2917 139

544.3489 140

515.3224

Example 1412-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-piperazin-1-yl]-4-trifluoromethyl-pyrimidine-5-carboxylicacid (2-hydroxy-ethyl)-methyl-amide

To a solution of2-[(R)-4-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-piperazin-1-yl]-4-trifluoromethyl-pyrimidine-5-carboxylicacid (45 mg, 0.1 mmol, 1 eq) in THF (2 mL) is added an excess of oxalylchloride (100 μL, 1.2 mmol, 12 eq,) and a catalytic amount of DMF, andthe resulting solution is stirred at rt for 45 min, at which timeN-2-hydroxyethyl, N-methyl amine (200 μL, 2.5 mmol, 25 eq) is added, andthe reaction is stirred for an additional 1 h. The reaction mixture isdiluted with EtOAc (50 mL) and washed with water (2×10 mL) followed bybrine (2×10 mL). The organic layer is dried over sodium sulfate andconcentrated under reduced pressure to a white residue. The desiredcompound is isolated by silica gel chromatography (CH₂Cl₂—20%MeOH/CH₂Cl₂) as a white solid (43 mg, 79%).

¹H NMR (400 MHz, MeOH-d₄) δ=8.55 (d, J=2.6 Hz, 1H), 7.22-7.29 (m, 2H),7.11-7.20 (m, 3H), 5.05-5.15 (m, 1H), 4.69-4.79 (m, 1H), 4.30 (s, 2H),3.80 (t, J=5.7 Hz, 2H), 3.66 (t, J=5.6 Hz, 2H), 3.50-3.60 (m, 2H),3.43-3.50 (m, 2H), 3.15 (dt, J=12.6 Hz, 4.2 Hz, 1H), 2.97-3.07 (m, 1H),2.35 (s, 3H), 2.16 (s, 3H), 1.45 (d, J=8.3 Hz, 3H).

HR MS (m/z, MH+) meas. 544.2647.

Example 142(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methoxy-methyl-amide

(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid (50 mg, 0.120 mmol) is dissolved in CH₂Cl₂ (300 μL). The mixture iscooled to 0° C. and oxalyl chloride (32 μL. 0.358 mmol) is addedfollowed by DMF (3 drops). While stirring, the reaction is warmed toroom temperature over 3 h. Diisopropylethylamine (209 μL, 1.2 mmol) isadded dropwise followed by addition of N,O-dimethylhydroxylaminehydrochloride (14 mg, 0.144 mmol). Allow the reaction to stir for 16 h.Concentrate the crude mixture in vacuo. The residue is purified by flashchromatography on silica gel (MeOH/CH₂Cl₂) to afford the title compound(42 mg, 76%).

Alternative Route to Prepare Example 95 Example 951-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2]bipyrazinyl-5′-yl]-ethanone

(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-carboxylicacid methoxy-methyl-amide (example 142, 450 mg, 0.975 mmol) is dissolvedin THF (1 mL) and cooled to 0° C. A dropwise addition of methylmagnesium iodide (325 μL, 0.975 mmol) is added dropwise. Reaction iswarmed to room temperature and continues to stir for 16 h. Add H₂O (1drop) and concentrate reaction mixture in vacuo. The residue is purifiedby flash chromatography on silica gel (60-100% EtOAc/Heptane and 0-8%MeOH/EtOAc) to afford the title compound (350 mg, 86%).

Example 143(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-5′-isopropenyl-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl

Methyltriphenylphosphonium iodide (410 mg, 1.010 mmol) is added to THF(5.5 mL) and cooled to 5° C. Potassium tert-butoxide (1.1 mL, 1M in THF,1.1 mmol) is added dropwise and the reaction is stirred for 30 min.1-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-ethanone(350 mg, 0.841 mmol) in THF (1.5 mL) is added to the reaction. Thereaction is allowed to stir 1 h at 5° C., and then the ice bath isremoved and the reaction is allowed to stir an additional 16 h at roomtemperature. Remove THF in vacuo. The residue is purified by flashchromatography on silica gel (60-90% EtOAc/heptane) to afford the titlecompound (130 mg, 37%).

Example 1442-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2]bipyrazinyl-5′-yl]-propane-1,2-diol

(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-5′-isopropenyl-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl(example 143, 120 mg, 0.290 mmol) is suspended in acetone (2 mL),tert-butanol (1 mL), and H₂O (1 mL). To this suspension is added K₂OsO₄(9.6 mg, 0.029 mmol) and NMO (37.4 mg, 0.319 mmol). The reaction isstirred at room temperature for 16 h. Concentrate in vacuo. Add H₂O andextract with EtOAc. Wash the combined organics with brine andconcentrate in vacuo. The residue is purified by flash chromatography onsilica gel (MeOH/CH₂Cl₂) to afford the title compound (49.2 mg, 38%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.32 (d, J=1.4 Hz, 1H), 8.27-8.16 (m, 1H),7.33-7.23 (m, 2H), 7.22-7.13 (m, 3H), 4.98 (d, J=1.0 Hz, 1H), 4.74-4.62(m, 1H), 4.58 (td, J=6.2 Hz, 1.0 Hz, 1H), 4.25 (s, 2H), 4.18 (dm, J=12.9Hz, 1H), 3.55-3.46 (m, 1H), 3.49 (d, J=5.8 Hz, 2H), 3.40 (dm, J=12.4 Hz,1H), 3.29 (td, J=12.5 Hz, 3.2 Hz, 1H), 3.07 (dd, J=12.3 Hz, 3.5 Hz, 1H),2.95 (td, J=12.3, 3.2 Hz, 1H), 2.26 (s, 3H), 2.12 (s, 3H), 1.36 (s, 3H),1.28 (d, J=6.4 Hz, 3 H).

HR MS (m/z, MH+) meas. 449.2667, calc. 449.2665.

Synthesis of Examples 145-158

General Protocol for the Amination of Pyridazine Chlorides XII withAmines to Yield Examples 145 to 154 (Route A)

To a solution of pyridazine chlorides XII (0.34 mmol) in NMP ordioxane/DMF (3 mL) is added the substituted piperazine (0.49 mmol) andTEA (0.15 mL, 1.08 mmol). The mixture is heated in a microwavesynthesizer at 210° C. for 60 min. Water is added and the resultingmixture is extracted with EtOAc. The combined organic layers are washedwith water, brine, dried over Na₂SO₄, filtered and concentrated down.The crude product is purified by chromatography on silica gel(EtOAc/Hexane: 10%˜70%) to give examples Ip

Examples 145-154

The following table (Table 9) lists examples of compounds prepared byamination as described above:

TABLE 9 HR MS [m/z, Example Structure MH+] meas. 145

433.2760 146

459.2924 147

428.2062 148

440.2065 149

446.1960 150

458.1984 151

472.2124 152

462 (MS) 153

450.2307 154

476.2472

Example 1554-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-piperazine-1-carboxylic acidphenyl ester

To a solution of 3-benzyl-4,5-dimethyl-6-piperazin-1-yl-pyridazine (60mg, 0.21 mmol) and phenyl chloroformate (40 mg, 0.26 mmol) in CH₂Cl₂ (3mL) at 25° C. is added N-methyl morpholine (0.07 mL, 0.60 mmol). Afterbeing stirred at 25° C. for 3 h, the mixture is diluted with CH₂Cl₂ (10mL), and washed with saturated sodium bicarbonate (1 mL) and water (2×5mL). The organic layer is concentrated and purified by HPLC (CH₃CN/H₂O:22%˜45% with 0.1% TFA) to give4-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-piperazine-1-carboxylic acidphenyl ester (69 mg, 81%).

¹H-NMR (400 MHz, CDCl₃) δ=2.28 (3H, s), 2.41 (3H, s), 3.40 (4H, d), 3.81(4H, d), 4.50 (2H, s), 7.13 (2H, d), 7.20 (2H, d), 7.27 (2H, m), 7.33(2H, m), 7.38 (2H, m).

HR MS (m/z, MH+) meas. 403.2115.

Example 1564-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-piperazine-1-carboxylic acidphenylamide

To a solution of 3-benzyl-4,5-dimethyl-6-piperazin-1-yl-pyridazine (60mg, 0.21 mmol)) in CH₂Cl₂ (5 mL) at 25° C. is added phenyl isocyanate(33 mg, 0.28 mmol). After being stirred at 25° C. for 2 h, the reactionmixture is concentrated and purified by HPLC (CH₃CN/H₂O: 22%˜45% with0.1% TFA) to give4-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-piperazine-1-carboxylic acidphenylamide (49 mg, 58%).

¹H-NMR (400 MHz, CDCl₃) δ=2.12 (3H, s), 2.21 (3H, s), 3.27 (4H, t), 3.67(4H, t), 4.30 (2H, s), 7.01 (1H, t), 7.19 (3H, m), 7.25 (4H, m), 7.39(2H, d).

HR MS (m/z, MH+) meas. 402.2279.

Example 1574-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-piperazine-1-carboxylic acidbenzylamide

To a solution of 3-benzyl-4,5-dimethyl-6-piperazin-1-yl-pyridazine (60mg, 0.21 mmol)) in CH₂Cl₂ (5 mL) at 25° C. is added benzyl isocyanate(37 mg, 0.28 mmol). After being stirred at 25° C. for 2 h, the reactionmixture is concentrated and purified by HPLC (CH₃CN/H₂O: 22%˜45% with0.1% TFA) to give4-(6-benzyl-4,5-dimethyl-pyridazin-3-yl)-piperazine-1-carboxylic acidbenzylamide (46 mg, 60%).

¹H-NMR (400 MHz, CDCl₃) δ=2.24 (3H, s), 2.34 (3H, s), 3.33 (4H, t), 3.58(4H, t), 4.44 (2H, s), 4.49 (2H, s), 7.19 (2H, d), 7.26 (2H, m), 7.30(2H, m), 7.32 (4H, m).

HR MS (m/z, MH+) meas. 416.2437.

Example 158 3-Benzyl-6-(4-benzyl-piperazin-1-yl)-4,5-dimethyl-pyridazine

To a solution of 3-benzyl-4,5-dimethyl-6-piperazin-1-yl-pyridazine (40mg, 0.14 mmol)) in CH₂Cl₂ (1.6 mL) and THF (1.6 mL) at 25° C. is addedbenzaldehyde (23 mg, 0.21 mmol), acetic acid (2 drops) and sodiumtriacetoxyborohydride (90 mg, 0.43 mmol). After being stirred at 25° C.for 2 h, the mixture is diluted with CH₂Cl₂ (10 mL) and washed withsaturated sodium bicarbonate (2 mL) and water (5 mL). The organic layeris concentrated and purified by HPLC (CH₃CN/H₂O: 22%˜45% with 0.1% TFA)to give 3-benzyl-6-(4-benzyl-piperazin-1-yl)-4,5-dimethyl-pyridazine (20mg, 37%).

¹H-NMR (400 MHz, MeOH-d₄) δ=2.00 (3H, s), 2.11 (3H, s), 2.56 (4H, t),3.12 (4H, t), 3.51 (2H, s), 4.16 (2H, s), 7.05 (3H, m), 7.15 (3H, m),7.25 (4H, m).

HR MS (m/z, MH+) meas. 373.2378.

5-membered arylmethyl-pyridazines

Scheme 7 shows a general synthetic scheme for the preparation ofcompounds of Formula Iq to Is. Substituted chloro pyridazines IIIa canbe reacted with acetonitrile under treatment with a strong base (e.gLiHMDS) to form intermediates XIVa. Hydrolysis of the nitrilefunctionality provides acid intermediates XIVb and subsequent amidcoupling with acid hydrazides yields intermediates XIVc. IntermediatesXIVa can be reacted with hydroxylamine andN,N-dimethylformamide-dimethylacetal to examples Iq or can providetetrazole examples Ir by reaction with sodium azide followed byalkylation (e.g. bromides or iodides). Intermediates XIVc can becondensed e.g. with triphenylphosphine to examples Is.

Synthesis of Intermediates XIV4,5-Dimethyl-6-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazin-3-yl-acetonitrile(Compound 67)

3-Chloro-4,5-dimethyl-6-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazine(1.0 g, 2.64 mmol), acetonitrile (0.225 mL, 4.22 mmol), and toluene (5mL) are combined and cooled to 0° C. LiHMDS (8.4 mL, 1.0 M, 8.4 mmol) isadded dropwise over 5 min. The reaction is stirred at 0° C. for 1 h,then warmed to room temperature and stirred an additional 16 h. Thereaction is quenched by the addition of saturated aq. NH₄Cl, and theorganics are extracted with EtOAc. The combined organic layers are driedover MgSO₄ and concentrated. The residue is purified by flashchromatography on silica gel (0-100% EtOAc in heptanes) to afford thetitle compound as an orange solid (500 mg, 50%).

¹H NMR (400 MHz, CDCl₃) δ=8.36 (s, 1H), 7.60 (dd, J=9.0 Hz, 2.5 Hz, 1H),6.65 (d, J=9.0 Hz, 1H), 3.96 (s, 2H), 3.72-3.78 (m, 4H), 3.26-3.37 (m,4H), 2.26 (d, J=13.1 Hz, 6H).

MS (m/z, MH+) meas. 377.2.

{4,5-Dimethyl-6-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazin-3-yl}-aceticacid (Compound 68)

{4,5-Dimethyl-6-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazin-3-yl}-acetonitrile(210 mg, 0.56 mmol) and 6 M HCl (1.0 mL) are added to a sealed tube andthen heated to 100° C. for 16 h. The organics are extracted with CH₂Cl₂.The aqueous portion is neutralized to pH ˜7 with sodium bicarbonatesolution and extracted with EtOAc. Target compound remains in theaqueous layer. This layer is concentrated under reduced pressure and theresidue is triturated several times with MeOH, and then dried in vacuoto afford the title compound (280 mg, quant).

Acetic acidN′-(2-{4,5-dimethyl-6-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazin-3-yl}-acetyl)-hydrazide(Compound 69)

Acetic acid hydrazide (20.6 mg, 0.28 mmol) is added to a round-bottomflask under N₂ followed by DMF (5 mL). Diisopropylethylamine (0.25 mL)is added and the reaction is stirred for 30 min.{4,5-Dimethyl-6-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazin-3-yl}-aceticacid (110 mg, 0.28 mmol) is added and the reaction is stirred for 1 h.HOBT (42 mg, 0.311 mmol) and HBTU (116.8 mg, 0.31 mmol) are added andthe reaction is allowed to stir for 16 h. The crude reaction mixture ispurified via flash chromatography on silica gel (0-30% methanol indichloromethane) to afford the title compound (114 mg, 90%).

Synthesis of Examples 159-162 Example 1594,5-Dimethyl-3-(5-methyl-[1,2,4]oxadiazol-3-yl-methyl)-6-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazine

4,5-Dimethyl-6-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazin-3-yl-acetonitrile(120 mg, 0.32 mmol) is combined with hydroxyl amine (63 mg, 0.96 mmol)and THF (2 mL). The reaction mixture is heated to reflux for 3 itConcentrate the reaction and redissolve the residue in dimethylacetamidedimethylacetal (500 μL). Heat this solution for 16 h at reflux.Concentrate the resulting mixture in vacuo. The residue is purified byflash chromatography on silica gel (MeOH/CH₂Cl₂) to afford the titlecompound (62.3 mg, 45%).

¹H NMR (400 MHz, DMSO-d₆) δ=8.44 (d, J=1.6 Hz, 1H), 7.83 (dd, J=9.1 Hz,2.5 Hz, 1H), 7.03 (d, J=9.1 Hz, 1H), 4.34 (s, 2H), 3.86-3.76 (m, 4H),3.26-3.18 (m, 4H), 2.54 (s, 3H), 2.27 (s, 3H), 2.22 (s, 3H).

HR MS (m/z, MH+): meas. 434.1913 calc. 434.1916.

Examples 160 and 1614,5-Dimethyl-3-(1-methyl-1H-tetrazol-5-ylmethyl)-6-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazine&4,5-Dimethyl-3-(2H-methyl-2H-tetrazol-5-ylmethyl)-6-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazine

4,5-Dimethyl-6-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazin-3-yl-acetonitrile(120 mg, 0.32 mmol) is combined with zinc (II) chloride (43.5 mg, 0.32mmol) and sodium azide (25 mg, 0.38 mmol) in H₂O (5 mL). The mixture isheated to reflux for 4 h, and then cooled to room temperature. The freetetrazole is isolated by filtration, dissolved in DMF (4.2 mL), andcarried on without further purification. Cesium carbonate (128.5 mg,0.395 mmol) is added and the reaction mixture is cooled to 0° C. Methyliodide (16 μL, 0.263 mmol) is added dropwise, and the reaction isstirred and allowed to warm to room temperature over 16 it Cool back to0° C. and add additional methyl iodide (24 μL, 0.395 mmol). Allowreaction to warm to room temperature over 16 h. Concentrate reaction invacuo and filter off solids. Wash with MeOH. Remaining solid isdissolved in H₂O and TFA and is purified by HPLC (CH₃CN/H₂O) to affordthe title compounds as a 57:43 mixture of regioisomers (22.2 mg, 20%).

¹H NMR (mixture of compounds, 600 MHz, DMSO-d₆) δ=8.44 (s, 1H), 7.83 (d,J=9.1 Hz, 1H), 7.07-6.99 (m, 1H), 4.62 (s, 1.1H), 4.50 (s, 0.9H), 4.30(s, 1.3H), 4.00 (s, 1.7H), 3.85-3.76 (m, 4 H), 3.24-3.16 (m, 4H), 2.29(s, 1.7H), 2.26 (s, 3H), 2.21 (s, 1.3H).

HR MS (m/z, MH+) meas. 434.2035, calc. 434.2029.

Example 1624,5-Dimethyl-3-(5-methyl-[1,3,4]oxadiazol-2-ylmethyl)-6-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazine

Acetic acidN′-(2-{4,5-dimethyl-6-[4-(5-trifluoromethyl-pyridin-2-yl)-piperazin-1-yl]-pyridazin-3-yl}-acetyl)-hydrazide(114 mg, 0.248 mmol) is added to a round-bottom flask under N₂ followedby acetonitrile (3 mL), diisopropylethylamine (0.27 mL, 1.43 mmol) andtriphenylphosphine (115.5 mg, 0.44 mmol) and the reaction is stirred for30 min. Hexachloroethane (77.5 mg, 0.329 mmol) is then added and thereaction is stirred for 16 h. The crude mixture is purified via HPLC(ammonium hydroxide as a modifier) to afford the title compound (8 mg,7%).

HR MS (m/z, MH+) meas. 434.1934, calc. 434.1916.

Synthesis of Examples 163 and 164

Examples 163 and 164 are prepared from incubation of 200 mg example 88with recombinant human Cyp3A4 to yield after isolation and purificationthe compounds mentioned below as white solids.

Example 1632-[(R)-4-(6-Benzyl-5-hydroxymethyl-4-methyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol

Yield: 6.5 mg

Example 1642-[(R)-4-(6-Benzyl-4-hydroxymethyl-5-methyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2]bipyrazinyl-5′-yl]-propan-2-ol

Yield: 8.2 mg

The compounds of the present invention are a species of a genus ofcompounds shown in U.S. provisional application 60/89,499. The followingis comparative data showing improvements in potency and solubility by acomparison of the closest examples, e.g., compound nos. 92, 93, 93a, b,c from application 60/89,499 with examples of the present invention:

Application 60/89,499

RGA RGA (25 nM (1 nM Smo Smo Mouse Human equilibrium Example agonist)agonist) Smo bdg., Smo bdg., solubility at no. IC₅₀ [nM] IC₅₀ [nM] IC₅₀[nM] IC₅₀ [nM] pH 6.8 [μM] 92 266 7558 197 247 <5 93 367 42 <5 93a 211356 61 <5 93b 168 529 139 204 <5 93c 22 236 62 101 <5

Examples of the Present Invention

RGA RGA (1 nM Smo (25 nM Smo Mouse Human equilibrium Example agonist)agonist) Smo bdg., Smo bdg., solubility at no. IC₅₀ [nM] IC₅₀ [nM] IC₅₀[nM] IC₅₀ [nM] pH 6.8 [μM] 2 2 23 8 4 48 2 25 8 5 425 50 6 114 3229 >1000 54 7 83 30 22 619 88 1 14 3 9 44 89 2 60 15 11 11 90 1 34 7 618 91 5 57 8 8 92 4 58 10 10 93 1 14 3 1 20 95 8 110 9 8 96 6 62 4 3 973 35 2 2 98 11 69 6 6 99 5 72 3 2 104 5 70 9 14 105 3 35 6 7 106 5 76 57 107 2 23 3 3 108 4 33 109 3 38 2 2 111 1 18 2 1 144 5 83 19 24 270Biological Activity

Activity of the compounds was evaluated using a reporter gene assay(RGA) in TMHh12 cells. IC₅₀ for antagonism of Gli-luciferase activitywas tested in the presence of increasing concentrations of a smallmolecule agonist which binds to Smo with 1 nM affinity and activates theHh pathway (Frank-Kamenetsky et al 2002, Journal of Biology 1,10.1-10.19). Antagonist compounds from screening which show increasedIC₅₀s for Gli-luc as the agonist dose is increased may be directlyinteracting with Smo (either through competition for the same bindingsite on Smo, or via competition between an active conformational stateof Smo that is induced by agonist and an inactive state that is inducedby the test antagonist). In validation experiments, a variety of smallmolecule antagonists of Smo demonstrate “IC₅₀ shift” behavior.

Table 10 lists the IC₅₀ of antagonists determined in the presence ofdifferent (1 nM and 25 nM) concentrations of a small agonist ofSmoothened (Frank-Kamenetsky et al 2002, Journal of Biology 1,10.1-10.19).

A Smo binding assay was developed using radio-labeled smoothened agonistfor compound competition. Table 10 lists the IC₅₀ for displacement of asmall molecule agonist of Smoothened determined in a filter bindingformat for the mouse and human Smoothened receptor.

TABLE 10 RGA RGA (1 nM Smo (25 nM Smo Mouse Human Example agonist)agonist) Smo bdg., Smo bdg., no. IC₅₀ [nM] IC₅₀ [nM] IC₅₀ [nM] IC₅₀ [nM]2 <0.1 <0.1 <0.1 <0.1 3 0.1-1    1-10 0.1-1   0.1-1   4 0.1-1    1-100.1-1   0.1-1   5 <0.1 0.1-1   <0.1 <0.1 6  1-10  1-25 <0.1 <0.1 7  1-10 1-25 <0.1 <0.1 8  1-10  1-25 0.1-1   0.1-1   9  1-10  1-25  1-10  1-1010 <0.1 <0.1 <0.1 11 <0.1  1-10 <0.1 12 <0.1 0.1-1   <0.1 <0.1 13 <0.1<0.1 <0.1 <0.1 14  1-10  1-25 0.1-1    1-10 15 <0.1 0.1-1   <0.1 <0.1 16<0.1 0.1-1   0.1-1   0.1-1   17 0.1-1   0.1-1   0.1-1   0.1-1   180.1-1    1-10 <0.1 <0.1 19 0.1-1   0.1-1   <0.1 <0.1 20 <0.1 0.1-1  <0.1 <0.1 21 0.1-1    1-10 <0.1 <0.1 22 0.1-1   0.1-1   0.1-1   0.1-1  23 0.1-1   0.1-1   <0.1 0.1-1   24 0.1-1   0.1-1   25 0.1-1    1-10 <0.1<0.1 26 0.1-1    1-10 0.1-1   0.1-1   27  1-10  1-10 0.1-1   0.1-1   28 1-10  1-10 <0.1 <0.1 29  1-10  1-10 <0.1 <0.1 30  1-10  1-10  1-10 1-10 31 <0.1 <0.1 <0.1 <0.1 32 <0.1 <0.1 <0.1 <0.1 33 <0.1 <0.1 <0.1<0.1 34 <0.1 0.1-1   <0.1 <0.1 35 <0.1 <0.1 <0.1 <0.1 36 <0.1 <0.1 <0.1<0.1 37 <0.1 0.1-1   0.1-1   <0.1 38 <0.1 0.1-1   <0.1 <0.1 39 <0.10.1-1   0.1-1   0.1-1   40 <0.1 0.1-1   0.1-1   0.1-1   41 0.1-1    1-25<0.1 0.1-1   42 <0.1 0.1-1   <0.1 <0.1 43 <0.1 <0.1 <0.1 <0.1 44 <0.10.1-1   0.1-1   0.1-1   45 0.1-1   0.1-1   <0.1 <0.1 46 <0.1 <0.1 <0.10.1-1   47 <0.1 <0.1 48 <0.1 <0.1 <0.1 <0.1 49 <0.1  1-10 0.1-1  0.1-1   50 <0.1 <0.1 <0.1 <0.1 51 52 <0.1 <0.1 <0.1 <0.1 53 <0.1  1-100.1-1   <0.1 54 <0.1 0.1-1   <0.1 <0.1 55 56 0.1-1    1-10  1-10  1-1057 0.1-1    1-25  1-10  1-10 58 0.1-1    1-10 0.1-1   0.1-1   59  1-10 1-25  1-25  1-10 60 0.1-1    1-10 0.1-1    1-10 61 0.1-1    1-10  1-10 1-10 62 0.1-1    1-25  1-10  1-10 63 0.1-1    1-10 0.1-1   0.1-1   64<0.1 0.1-1   65 0.1-1   0.1-1   <0.1 0.1-1   66 <0.1 0.1-1   <0.1 <0.167 0.1-1    1-10 <0.1 0.1-10  68 0.1-1   0.1-1   0.1-1   0.1-1   69 70<0.1 <0.1 <0.1 <0.1 72 <0.1 0.1-1   <0.1 <0.1 73 <0.1 0.1-1   <0.1 <0.175 0.1-1    1-10 <0.1 <0.1 78 <0.1  1-10 <0.1 <0.1 79 0.1-1    1-10 1-10  1-25 80 0.1-1   0.1-1   <0.1 <0.1 81 <0.1 0.1-1   <0.1 <0.1 83<0.1 0.1-1   <0.1 <0.1 87 <0.1 0.1-1   <0.1 <0.1 88 <0.1 <0.1 <0.1 <0.189 <0.1 <0.1 <0.1 <0.1 90 <0.1 <0.1 <0.1 <0.1 91 <0.1 <0.1 <0.1 <0.1 92<0.1 <0.1 <0.1 <0.1 93 <0.1 <0.1 <0.1 <0.1 94 <0.1 0.1-1   <0.1 <0.1 95<0.1 0.1-1   <0.1 <0.1 96 <0.1 <0.1 <0.1 <0.1 97 <0.1 <0.1 <0.1 <0.1 98<0.1 <0.1 <0.1 <0.1 99 <0.1 <0.1 <0.1 <0.1 100 <0.1 0.1-1   <0.1 <0.1101 <0.1 0.1-1   <0.1 <0.1 102 <0.1 0.1-1   <0.1 <0.1 104 <0.1 <0.1 <0.1<0.1 105 <0.1 <0.1 <0.1 <0.1 106 <0.1 <0.1 <0.1 <0.1 107 <0.1 <0.1 <0.1<0.1 108 <0.1 <0.1 109 <0.1 <0.1 <0.1 <0.1 110 <0.1 <0.1 <0.1 <0.1 111<0.1 <0.1 <0.1 <0.1 112 <0.1 <0.1 <0.1 <0.1 113 <0.1 0.1-1   <0.1 <0.1114 <0.1 0.1-1   <0.1 <0.1 115 0.1-1    1-10 0.1-1   0.1-1   116  1-10 1-25  1-25 0.1-1   117  1-10  1-25  1-10  1-10 118 <0.1 0.1-1   <0.10.1-1   119 <0.1 <0.1 <0.1 <0.1 120 <0.1 0.1-1   0.1-1   0.1-1   121<0.1 <0.1 <0.1 <0.1 122 0.1-1    1-10 0.1-1   0.1-1   123 <0.1 0.1-1  <0.1 0.1-1   125 <0.1 0.1-1   0.1-1   0.1-1   126 <0.1 0.1-1   <0.1 <0.1127 <0.1 0.1-1   0.1-1   0.1-1   128 <0.1 0.1-1   <0.1 0.1-1   129 <0.10.1-1   0.1-1   0.1-1   130 <0.1 0.1-1   <0.1 <0.1 131 0.1-1    1-100.1-1   0.1-1   132 <0.1 0.1-1   <0.1 0.1-1   133 <0.1 0.1-1   <0.1 <0.1134 <0.1 0.1-1   <0.1 <0.1 135 <0.1 0.1-1   <0.1 <0.1 136 <0.1 0.1-1  <0.1 0.1-1   137 0.1-1   0.1-1   0.1-1   0.1-1   138 <0.1 0.1-1  0.1-1   0.1-1   139 0.1-1    1-10  1-10  1-10 140 <0.1  1-10 0.1-1  0.1-1   141 <0.1 0.1-1   <0.1 <0.1 143 <0.1 <0.1 <0.1 <0.1 144 <0.1 <0.1<0.1 <0.1 145 0.1-1   0.1-1   0.1-1   0.1-1   146 <0.1 <0.1 0.1-1  0.1-1   147 <0.1 0.1-1   0.1-1   0.1-1   148 <0.1 0.1-1   <0.1 <0.1 149<0.1 0.1-1   <0.1 <0.1 150 <0.1 0.1-1   <0.1 <0.1 151 <0.1 0.1-1  0.1-1   0.1-1   153 <0.1 <0.1 <0.1 <0.1 154 0.1-1    1-10 <0.1 <0.1 155<0.1 0.1-1   0.1-1   0.1-1   156 <0.1 0.1-1   <0.1 0.1-1   157 <0.10.1-1   <0.1 0.1-1   158  1-10  1-25  1-10  1-10 159 0.1-1    1-10  1-10 1-10 160/161  1-10  1-25  1-10  1-10 162 0.1-1    1-25  1-25  1-25 163<0.1 <0.1 <0.1 <0.1 164 <0.1 <0.1 <0.1 <0.1

Thus while there have been described what are presently believed to bepreferred embodiments of the invention, those skilled in the art willrealize that changes and modifications may be made thereto withoutdeparting from the spirit of the invention, and it is intended to claimall such changes and modifications as fall within the true scope of theinvention.

What is claimed is:
 1. A compound of formula (Ia):

or a pharmaceutically acceptable salt thereof, wherein R11 is selectedfrom C₁₋₈ alkyl, C₂₋₈ alkenyl, C₃₋₁₄ cycloalkyl, a C₆₋₁₄ aryl group, a5-14 membered heteroaryl group, a 3-14 membered cycloheteroalkyl group,C₁₋₈ alkoxy, halo, NR13R14, C(O)OR13, C(O)NR13R14, C₁₋₈haloalkyl,formyl, carbalkoxy, C₁₋₈alkylOH, C(O)R13, SO₂R13, C(O)NHC₁₋₈alkylR13,NR13R14, SO₂NR13R14, OCF₃, NHC(O)R13, CH₂OC(O)NR13R14, CH₂NR13R14,NHC(O)OR13, NHC(O)NR13R14, CH₂NHSO₂R13, CH₂NHC(O)OR13, OC(O)R13, andNHC(O)R13; R12 is selected from H, C₁₋₈ alkyl, a C₆₋₁₄ aryl group, C₁₋₈haloalkyl, C₁₋₈ alkoxy, halo, NH₂, CN, OCF₃, OH, C(O)NR13R14, C(O)R13,NR13R14, NHC(O)R13, SO₂R13, and SO₂NR13R14; and R13 and R14 areindependently selected from H, C₁₋₈ alkyl, C₂₋₈ alkenyl, C₃₋₁₄cycloalkyl, a C₆₋₁₄ aryl group, a 5-14 membered heteroaryl group, a 3-14membered cycloheteroalkyl group, C₁₋₈haloalkyl, C₁₋₈ alkylOH, andC₁₋₈alkoxy.
 2. The compound of claim 1 selected from:2-[(R)-4-(4,5-Dimethyl-6-phenoxy-pyridazin-3-yl)-2-methyl-3,4,5,6-tetra-hydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol;2-[(R)-4-(6-(Hydroxyl-phenyl-methyl)-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2]bipyrazinyl-5′-yl]-propan-2-ol;2-[(R)-4-(4,5-Dimethyl-6-pyridin-4-ylmethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol;2-[(R)-4-(4,5-Dimethyl-6-pyridin-2-ylmethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol;2-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol;2-[4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol;2-[(S)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol;2-[(R)-4-6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-ethyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propan-2-ol;1-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-ethanone;and2-[(R)-4-(6-Benzyl-4,5-dimethyl-pyridazin-3-yl)-2-methyl-3,4,5,6-tetrahydro-2H-[1,2′]bipyrazinyl-5′-yl]-propane-1,2-diol.3. A pharmaceutical composition comprising a compound according to claim1 and a pharmaceutically acceptable carrier.
 4. A compound of formula:

or a pharmaceutically acceptable salt thereof.